class Solution {

public:

    vector<int> fairCandySwap(vector<int>& A, vector<int>& B) {

        int sumA = , sumB = , delta = ;

        unordered_set<int> setA;

        for(auto a:A)

        {

            sumA += a;

            setA.insert(a);//err...

        }

        for(auto b:B) sumB += b;

        delta = (sumA-sumB)/;

        for(auto b:B)

        {

            if(setA.count(delta+b)) return {delta+b, b};

        }

        return vector<int>();

    }

};