#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    cout << s;
    return;
  }
  if (n == 1)
    cout << "0";
  else {
    if (s[0] > '1') {
      s[0] = '1';
      k--;
    }
    for (long long int i = 1; i < n && k > 0; i++) {
      if (s[i] > '0') {
        s[i] = '0';
        k--;
      }
    }
    cout << s;
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long int t;
  t = 1;
  while (t--) {
    solve();
    cout << '\n';
  }
  return 0;
}
