#include <bits/stdc++.h>
using namespace std;
struct abc {
  long long int x, y;
};
bool compare(abc a1, abc a2) {
  if (a1.x == a2.x) return a1.y < a2.y;
  return a1.x < a2.x;
}
const long long int mod = 1e9;
long long int a[200005];
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long int n, k;
  string s;
  cin >> n >> k >> s;
  if (k == n && n == 1) {
    cout << 0;
    return 0;
  }
  for (long long int i = 0; i < n && k; i++) {
    if (i == 0 && s[i] != '1')
      k--, s[i] = '1';
    else if (s[i] != '0' && i != 0)
      s[i] = '0', k--;
  }
  cout << s;
}
