#include <bits/stdc++.h>
using namespace std;
int n, k;
int a[500005];
int main() {
  cin >> n >> k;
  for (int i = 1; i <= n; i++) {
    char c;
    cin >> c;
    a[i] = c - '0';
  }
  if (n == 1) {
    if (k >= 1)
      cout << 0;
    else
      cout << a[1];
    return 0;
  }
  int sum = k;
  for (int i = 1; i <= n; i++) {
    if (sum == 0) break;
    if (i == 1 && a[i] != 1) {
      sum--;
      a[i] = 1;
    } else if (i != 1 && a[i] != 0) {
      sum--;
      a[i] = 0;
    }
    if (sum == 0) break;
  }
  for (int i = 1; i <= n; i++) cout << a[i];
  return 0;
}
