#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
const int inf = 1e9 + 1;
const double eps = 1e-15;
const double EPS = 1e-9;
const double PI = acos(-1.0);
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    if (s[0] != '0' && k) {
      cout << 0;
    } else
      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;
  return 0;
}
