#include <bits/stdc++.h>   int main() {     int n;     std::string s;     std::cin >> n >> s;     int cnt = 0;     for (int i = 0; i < s.length(); i++) {       if (s[i] ==  1 )         cnt++;       else {         std::cout << cnt;         cnt = 0;       }     }     std::cout << cnt;     return 0;   }   