#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18;
const long long MAXN = 1e8;
const double pi = acos(-1);
long long n, k, i, l;
string s;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  cin >> s;
  if (n == 1 and k > 0) return cout << 0 << endl, 0;
  l = s[0] - '0';
  if (l > 1 and k > 0) {
    k--;
    cout << 1;
  } else
    cout << s[0];
  l = 0;
  for (i = 1; i < s.size(); i++) {
    if (k > 0) {
      l = s[i] - '0';
      if (l > 0) {
        cout << 0;
        k--;
        continue;
      }
    }
    cout << s[i];
  }
  return 0;
}
