#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  char S[200005];
  cin >> n >> k >> S;
  if (k > 0) {
    if (n > 1) {
      if (S[0] != '1') {
        S[0] = '1';
        k--;
      }
      for (int i = 1; i < n && k != 0; i++) {
        if (S[i] != '0') {
          S[i] = '0';
          k--;
        }
      }
    } else
      S[0] = '0';
  }
  cout << S << endl;
  return 0;
}
