#include <bits/stdc++.h>   using namespace std;   int main() {     int n, b, one, two;     string a;     one = 0;     two = 0;     cin >> n >> a;     for (b = 0; b < n; b++) {       if (a[b] ==  1 ) {         one++;       } else {         two++;       }     }     if (one > two) {       cout << one - two;     } else {       cout << two - one;     }   }   