#include <bits/stdc++.h>
using namespace std;
void solution(long long n, long long k, string s) {
  long long val = k;
  if (s[0] != '1' && val > 0 && n != 1) {
    s[0] = '1';
    val--;
  }
  if (n == 1 && val > 0) {
    s[0] = '0';
  }
  for (long long i = 1; i < n; i++) {
    if (s[i] != '0' && val > 0) {
      s[i] = '0';
      val--;
    }
    if (val == 0) break;
  }
  cout << s << endl;
}
int main() {
  long long t;
  t = 1;
  while (t--) {
    long long n, k;
    cin >> n >> k;
    string s;
    cin >> s;
    solution(n, k, s);
  }
}
