#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using pi = pair<int, int>;
void setIO(string name = "contest") {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  freopen((name + ".in").c_str(), "r", stdin);
  freopen((name + ".out").c_str(), "w", stdout);
}
ll MOD = 1000000007;
int main() {
  int n, m;
  cin >> n >> m;
  string str;
  cin >> str;
  if (str.length() == 1 && m != 0) {
    cout << 0 << "\n";
  } else {
    for (int i = 0; i < str.length(); i++) {
      if (!i && str[i] != '1' && m > 0) {
        str[i] = '1';
        m--;
      } else if (str[i] != '0' && i && m > 0) {
        str[i] = '0';
        m--;
      }
      if (m <= 0) {
        break;
      }
    }
    cout << str << "\n";
  }
}
