#include <bits/stdc++.h>
using namespace std;
const long long N = 1e6 + 1;
map<long long, long long> mp, pm;
deque<long long> v, vc, ve, vv, vd;
deque<char> p, pe;
deque<string> ts, ss, st;
deque<double> sd, ds;
long long a, b, c, d, e, f, cnt, ans, r, n, l, x, y;
long double q, t, cnt1, cnt2;
string g, h, w, o, m, s;
char z, u;
bool re, rt;
vector<pair<long long, long long> > pr, rp, pp;
map<pair<long long, long long>, long long> aw, wa;
int main() {
  cin.tie(NULL);
  cout.tie(NULL);
  ios_base::sync_with_stdio(0);
  cin >> a >> b;
  cin >> g;
  if (a == 1) {
    if (b != 0) {
      cout << 0;
    } else if (b == 0) {
      cout << g;
    }
    return 0;
  }
  if (g[0] != '1' and b != 0) g[0] = '1', b--;
  for (long long i = 1; i < g.size(); i++) {
    if (g[i] != '0' and b != 0) {
      g[i] = '0';
      b--;
    }
  }
  cout << g;
}
