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class Solution:
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    def restoreIpAddresses(self, s: str):
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        def isValid(st):
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            if len(st) != len(str(int(st))):
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                return False
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            st = int(st)
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            if st > 255 or st < 0:
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                return False
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            return True
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        validIps = []
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        for i in range(1, 4):
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            s1 = s[:i]
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            if not isValid(s1):
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                continue
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            for j in range(i + 1, min(len(s), i + 4)):
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                s2 = s[i:j]
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                if not isValid(s2):
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                    continue
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                for k in range(j + 1, min(len(s), j + 4)):
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                    s3 = s[j:k]
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                    if not isValid(s3):
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                        continue
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                    s4 = s[k:]
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                    if not isValid(s4):
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                        continue
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                    currentIp = s1 + "." + s2 + "." + s3 + "." + s4
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                    validIps.append(currentIp)
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        return validIps