#include <bits/stdc++.h>
int main() {
  int n, k;
  scanf("%d %d", &n, &k);
  char a[n];
  scanf(" %s", &a);
  if (k == 0)
    puts(a);
  else if (n == 1)
    printf("0");
  else if (k > 0) {
    if (a[0] == '1' && n > 1) k++;
    a[0] = '1';
    for (int i = 1; i < k && a[i] != '\0'; i++) {
      if (a[i] == '0') k++;
      a[i] = '0';
    }
    for (int i = 0; a[i] != '\0'; i++) printf("%c", a[i]);
  }
  return 0;
}
