#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, k, x;
  cin >> n >> k;
  x = k;
  char s[200001];
  cin >> s;
  for (long long int i = 0; i < n; i++) {
    if (k == 0) {
      break;
    } else {
      if (i == 0) {
        if (s[i] != '1') {
          s[i] = '1';
          k--;
        }
      } else if (i != 0) {
        if (s[i] != '0') {
          s[i] = '0';
          k--;
        }
      }
    }
  }
  if (n == 1 && x != 0) {
    cout << "0" << endl;
    return 0;
  }
  cout << s << endl;
  return 0;
}
