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