#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  string s;
  cin >> n >> k >> s;
  for (int i = 0; i < n; i++) {
    char c = (i || n == 1) ? '0' : '1';
    if (k && s[i] != c) {
      s[i] = c;
      k--;
    }
  }
  cout << s << endl;
}
