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