#include <bits/stdc++.h>
using namespace std;
void logf(istream_iterator<string> it) {}
template <typename T, typename... Args>
void logf(istream_iterator<string> it, T a, Args... args) {
  cout << *it << "=" << a << " ";
  logf(++it, args...);
}
const double PI = acos(-1);
void solve() {
  int n;
  cin >> n;
  ;
  int k;
  cin >> k;
  ;
  string s;
  cin >> s;
  ;
  if (s.size() == 1 && k > 0) {
    s[0] = '0';
    cout << s << endl;
    return;
  }
  for (int i = 0; i < n && k > 0; i++) {
    if (i == 0) {
      if (s[0] != '1') {
        s[0] = '1';
        k--;
      }
    } else if (s[i] > '0') {
      s[i] = '0';
      k--;
    }
  }
  cout << s << endl;
}
int main() {
  cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
  solve();
}
