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