#include <bits/stdc++.h>
using namespace std;
const int N = 1005;
int main() {
  string s;
  int n, k;
  cin >> n >> k >> s;
  if (n == 1) {
    if (k)
      puts("0");
    else
      cout << s;
    return 0;
  }
  if (s[0] != '1' && k > 0) {
    s[0] = '1';
    k--;
  }
  for (int i = 1; k > 0 && i < n; i++) {
    if (s[i] != '0' && k > 0) {
      s[i] = '0';
      k--;
    }
  }
  cout << s;
}
