#include <bits/stdc++.h>   using namespace std;   int fun(string s, int i) {     int k = 0;     while (s[i] ==  0  & i >= 0) {       k++;       i--;     }     return k;   }   int main(int argc, char const *argv[]) {     string s;     int a, k = 0, count = 1;     cin >> a;     cin >> s;     string ans =   ;     int i = s.size() - 1;     if (s[i] ==  0 ) {       while (s[i] ==  0 ) {         ans = ans +  0 ;         i--;       }     }     while (i >= 0) {       k = 0;       if (s[i] ==  1 ) {         while (s[i] ==  1  && i >= 0) {           k++;           i--;         }         ans = ans + char( 0  + k);       } else if (s[i] ==  0 ) {         int t = fun(s, i);         i = i - t;         while (t > 1) {           ans = ans +  0 ;           t = t - 1;         }       }     }     reverse(ans.begin(), ans.end());     int myint1 = stoi(ans);     cout << myint1;     return 0;   }   