class Solution {
public:
    bool checkAlmostEquivalent(string word1, string word2) {
        unordered_map<char,int> hash;
        for(auto& ch: word1)
            hash[ch]++;
        for(auto& ch: word2)
            hash[ch]--;
        
        for(auto&& x : hash)
        {
            if(abs(x.second) > 3)
            return false;
        }

        return true;
    }
};