#include <bits/stdc++.h>   using namespace std;   using ll = long long;   const int maxn = 1e5 + 5;   string s;   set<pair<int, int>> t;   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cin >> s;     int cnt = 0;     for (int i = (int)s.size() - 1; i >= 0; i--) {       if (s[i] ==  0 )         cnt++;       else {         if (cnt)           cnt--;         else           s[i] =  0 ;       }     }     cout << s;   }   