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