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class Solution {
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 public:
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  string reformatNumber(string number) {
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    string temp; // stores the digits from string number
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    string ans;  // stores final answer
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    int n = number.size();
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    for (auto ch : number)
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      if (isdigit(ch)) temp += ch;
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    int len = temp.size();
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    int i = 0;
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    while (len > 0) {
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      // check for different values of "len"
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      if (len > 4) { // if len > 4 -> make grp of 3 digits
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        ans += temp.substr(i, i + 3);
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        temp.erase(i, 3);
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        len = len - 3;
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        ans += "-";
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      }
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      else if (len == 3) { // if len == 3 -> make grp of 3 digits
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        ans += temp.substr(i, i + 3);
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        temp.erase(i, 3);
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        len = len - 3;
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        ans += "-";
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      }
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      else if (len == 2) { // if len == 2 -> make grp of 2 digits
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        ans += temp.substr(i, i + 2);
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        temp.erase(i, 2);
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        len = len - 2;
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        ans += "-";
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      }
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      else if (len == 4) { // if len == 4 -> make 1 grp of 2 digits & reduce the
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                           // length by 2 units, in the next iteration it will
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                           // automatically catch (len==2) condition
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        ans += temp.substr(i, i + 2);
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        temp.erase(i, 2);
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        ans += "-";
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        // ans += temp.substr(i,i+2); ------(1)
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        // temp.erase(i,2); ------(2)
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        // ans += "-"; ------(3)
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        len = len - 2; // *len = len-4* can be edited to *len = len-2*------(4)
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      }
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    }
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    ans.pop_back();
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    return ans;
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  }
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};