#include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     cin >> n >> k;     string K;     cin >> K;     if (K.size() == 1 and k != 0) {       cout << 0;       return 0;     }     if (k == 0) {       cout << K;       return 0;     }     if (K[0] !=  1 ) {       K[0] =  1 ;       k -= 1;       for (int i = 1; i < n; ++i) {         if (k == 0) {           cout << K;           return 0;         }         if (K[i] !=  0 ) {           K[i] =  0 ;           k--;         }       }     } else {       for (int i = 1; i < n; ++i) {         if (k == 0) {           cout << K;           return 0;         }         if (K[i] !=  0 ) {           K[i] =  0 ;           k--;         }       }     }     cout << K;     return 0;   }   