#include <bits/stdc++.h>
using namespace std;
template <typename a>
void SWAP(a &b, a &c) {
  a d = b;
  b = c;
  c = d;
}
long long power(long long a, long long b) {
  long long result = 1;
  while (b) {
    if (b & 1) result = a * result;
    a *= a;
    b >>= 1;
  }
  return result;
}
long long gcd(long long a, long long b) {
  while (b) {
    a = a % b;
    SWAP(a, b);
  }
  return a;
}
long long lcm(long long a, long long b) { return (a * (b / gcd(a, b))); }
string solve(string a, long long n, long long k) {
  string ans;
  for (long long i = 0, j = 0; i < n && j < k; i++) {
    if (i == 0) {
      if (n == 1) {
        a[i] = '0';
        j++;
      } else if (a[i] != '1') {
        a[i] = '1';
        j++;
      }
    } else {
      if (a[i] != '0') {
        a[i] = '0';
        j++;
      }
    }
  }
  return a;
}
int main() {
  long long n, k;
  cin >> n >> k;
  string str;
  cin >> str;
  str = solve(str, n, k);
  cout << str << endl;
  return 0;
}
