#include <bits/stdc++.h>
using namespace std;
const int maxn = 4;
int n, k;
string s;
int main() {
  std::ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> k >> s;
  if (!k) {
    cout << s << endl;
    return 0;
  }
  if (n == k and k == 1) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 0; i < k; i++) {
    if (!i and s[i] > '1') {
      s[i] = '1';
    } else if ((!i and s[i] == '1') or (i and s[i] == '0') and k < n) {
      k++;
      continue;
    } else {
      s[i] = '0';
    }
  }
  cout << s << endl;
  return 0;
}
