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