#include <bits/stdc++.h>
using namespace std;
string s[60];
int main() {
  long long i, j, k, n, m;
  string s;
  cin >> n >> k >> s;
  if (k == n && k == 1)
    cout << 0 << endl;
  else {
    if (s[0] != '1' && k >= 1) {
      k--;
      s[0] = '1';
    }
    for (i = 1; i < n && k > 0; i++) {
      if (s[i] != '0') {
        k--;
        s[i] = '0';
      }
    }
    cout << s << endl;
  }
  return 0;
}
