#include <bits/stdc++.h>
using namespace std;
const int M = 1200000;
const int inf = 0x3f3f3f3f;
int n, m, k;
char s[M];
int main() {
  cin >> n >> k >> s;
  if (n == 1) {
    if (k) s[0] = '0';
    cout << s << endl;
    return 0;
  }
  if (k && s[0] != '1') {
    --k;
    s[0] = '1';
  }
  for (int i = (1); i <= (n - 1); ++i) {
    if (k && s[i] != '0') {
      --k;
      s[i] = '0';
    }
  }
  cout << s << endl;
  return 0;
}
