#include <bits/stdc++.h>
using namespace std;
long long min(long long a, long long b) { return a < b ? a : b; }
int ceil(int a, int b) { return (a + b - 1) / b; }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (!k) {
    cout << s;
    return 0;
  }
  if (s.length() == 1) {
    cout << 0;
    return 0;
  }
  int cnt = 0;
  if (s[0] != '1') s[0] = '1', cnt++;
  for (int i = 1; i <= s.length(); i++) {
    if (cnt == k) break;
    if (s[i] != '0') s[i] = '0', cnt++;
  }
  cout << s;
}
