#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1 && k >= 1) {
    cout << 0;
    return 0;
  }
  long long i = 0;
  while (k != 0 && i < (int)s.length()) {
    if (i == 0 && s[i] != '1') s[i] = '1', k--;
    if (i != 0 && s[i] != '0') s[i] = '0', k--;
    i++;
  }
  cout << s;
  return 0;
}
