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class Solution {
public:
    int maxProduct(vector<string>& words) {
        unordered_map<int, int> maskLen;
        int ans = 0;
        for(auto word: words){
            int mask = 0;
            for(char ch: word)
                mask |= (1<<(ch-'a'));
            maskLen[mask] = max(maskLen[mask], int(word.length()));

            for(auto &mLen: maskLen)
                if(!(mask & mLen.first))
                    ans = max(ans, int(mLen.second*word.length()));
        }
        return ans;
    }
};