#include <bits/stdc++.h>
using namespace std;
template <typename T, typename T1>
T amax(T& a, T1 b) {
  if (b > a) a = b;
  return a;
}
template <typename T, typename T1>
T amin(T& a, T1 b) {
  if (b < a) a = b;
  return a;
}
const long long N = 200005, INF = 2000000000000000000;
const long long SIX = 1000000;
bool prime(long long n) {
  long long i = 0;
  for (i = 2; i * i <= n; i++) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
void solve() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  long long i = 0;
  long long ans = 0;
  if (n == 1 && k != 0) {
    cout << "0";
    return;
  }
  for (i = 0; i < n; i++) {
    if (i == 0 && ans < k) {
      if (s[i] != '1') {
        s[i] = '1';
        ans++;
      }
    } else if (i > 0 && ans < k) {
      if (s[i] != '0') {
        s[i] = '0';
        ans++;
      }
    }
  }
  cout << s << "\n";
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  long long t;
  t = 1;
  while (t--) solve();
}
