#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("avx2")
using namespace std;
signed main() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1 && k > 0) {
    s[0] = '0';
  } else if (k > 0 && s[0] != '1') {
    s[0] = '1';
    --k;
  }
  long long i = 1;
  while (i < n && k > 0) {
    if (s[i] != '0') {
      --k;
      s[i] = '0';
    }
    ++i;
  }
  cout << s << '\n';
  return 0;
}
