#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void solve() {
  ll n, k, flag = 0;
  string second;
  cin >> n >> k >> second;
  if (n == 1) {
    if (k > 0) {
      cout << 0;
    } else {
      cout << second[0];
    }
  } else {
    for (ll i = 0; i < n; i++) {
      if (k == 0) break;
      if (i == 0) {
        if (second[i] == '1')
          continue;
        else {
          second[i] = '1';
          k--;
        }
      } else {
        if (second[i] == '0')
          continue;
        else {
          second[i] = '0';
          k--;
        }
      }
    }
    cout << second;
  }
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
