class Solution {
public:
    char findTheDifference(string &s, string &t) {
    int f = 0;
    int n = 0;
    for (int i = 0; i < s.size(); ++i) {
        f += s[i];
        n += t[i];
    }
    n += t[t.size() - 1];
    return n - f;
    }
};