#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1);
int dx[] = {1, 0, 0, -1};
int dy[] = {0, 1, -1, 0};
int main() {
  cin.tie(0);
  std::ios::sync_with_stdio(false);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (s.size() == 1) {
    if (k) {
      s[0] = '0';
    }
    cout << s;
    return 0;
  }
  if (s[0] != '1' && k) {
    s[0] = '1';
    k--;
  }
  for (int i = 1; i < n && k; i++) {
    if (s[i] != '0') {
      s[i] = '0';
      k--;
    }
  }
  cout << s;
}
