#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  int cnt = 0;
  if (n == 1) {
    if (k == 1) {
      cout << 0;
      return 0;
    } else {
      cout << s;
      return 0;
    }
  }
  if (k == 0) {
    cout << s;
    return 0;
  } else {
    if (s[0] != '1') s[0] = '1', k--;
    for (int i = 1; i < n && k != 0; i++)
      if (s[i] != '0') s[i] = '0', k--;
    cout << s;
  }
  return 0;
}
