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class Solution {
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 public:
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  bool checkforIPv6(string IP) {
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    int n = IP.size();
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    vector<string> store;
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    string s = "";
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    for (int i = 0; i < n; i++) {
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      if (IP[i] == ':') {
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        store.push_back(s);
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        s = "";
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      } else {
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        s += IP[i];
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      }
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    }
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    store.push_back(s);
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    if (store.size() != 8) {
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      return false;
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    }
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    for (int i = 0; i < store.size(); i++) {
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      string s = store[i];
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      if (s.size() > 4 or s.size() == 0) {
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        return false;
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      }
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      for (int j = 0; j < s.size(); j++) {
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        if (s[j] >= 'a' and s[j] <= 'f') {
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          continue;
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        } else if (s[j] >= 'A' and s[j] <= 'F') {
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          continue;
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        } else if (s[j] >= '0' and s[j] <= '9') {
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          continue;
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        } else {
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          return false;
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        }
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      }
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    }
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    return true;
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  }
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  bool checkforIPv4(string IP) {
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    int n = IP.size();
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    vector<string> store;
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    string s = "";
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    for (int i = 0; i < n; i++) {
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      if (IP[i] == '.') {
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        store.push_back(s);
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        s = "";
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      } else {
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        s += IP[i];
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      }
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    }
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    store.push_back(s);
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    if (store.size() != 4) {
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      return false;
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    }
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    for (int i = 0; i < store.size(); i++) {
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      string s = store[i];
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      if (s.size() > 3 or s.size() == 0) {
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        return false;
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      }
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      int num = 0;
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      for (int j = 0; j < s.size(); j++) {
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        if (s.size() >= 2 and s[0] == '0' and s[1] == '0') {
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          return false;
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        }
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        if (s.size() >= 2 and s[0] == '0' and s[1] != '0') {
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          return false;
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        }
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        if (s[j] >= '0' and s[j] <= '9') {
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          // Do nothing.
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        } else {
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          return false;
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        }
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        num = num * 10 + (s[j] - '0');
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      }
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      if (num > 255 or num < 0) {
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        return false;
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      }
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    }
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    return true;
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  }
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  string validIPAddress(string queryIP) {
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    bool IPv6 = checkforIPv6(queryIP);
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    bool IPv4 = checkforIPv4(queryIP);
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    if (IPv6) {
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      return "IPv6";
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    }
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    if (IPv4) {
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      return "IPv4";
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    }
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    return "Neither";
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  }
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};