#include <bits/stdc++.h>
using namespace std;
void solve();
int main() {
  ios_base::sync_with_stdio(0);
  cout.tie(0);
  cin.tie(0);
  solve();
}
int n, k;
string s;
void solve() {
  cin >> n >> k >> s;
  if (n == 1 && k == 1) {
    cout << "0" << '\n';
    return;
  }
  for (int i = 0; i < n && k > 0; ++i) {
    if (i == 0 && s[i] != '1') {
      s[i] = '1';
      --k;
    } else if (i != 0 && s[i] != '0') {
      s[i] = '0';
      --k;
    }
  }
  cout << s << '\n';
}
