#include <bits/stdc++.h>
using namespace std;
mt19937_64 rang(
    chrono::high_resolution_clock::now().time_since_epoch().count());
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  srand(chrono::high_resolution_clock::now().time_since_epoch().count());
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    if (s[0] != '0' && k >= 1)
      cout << 0 << "\n";
    else if (s[0] != '0' && k == 0)
      cout << s[0] << "\n";
    else
      cout << s[0] << "\n";
  } else {
    for (int i = 0; i < s.length() && k > 0; i++) {
      if (i == 0) {
        if (s[i] != '1') {
          s[i] = '1';
          k--;
        }
      } else if (s[i] != '0' && (i > 0 && i <= n - 1)) {
        s[i] = '0';
        k--;
      }
    }
    cout << s << "\n";
  }
  return 0;
}
