#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <forward_list>
#include <fstream>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <streambuf>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <valarray>
#include <vector>

using namespace std;

using ll = long long;
using cd = complex<double>;

constexpr ll mod = 1e9 + 7, maxn = 3e5 + 10;

ll lgput(ll x, ll y, ll r) { return y == 0 ? r : lgput(x * x % mod, y / 2, y % 2 ? x * r % mod : r); }

ll gcd(ll x, ll y) { return y == 0 ? x : gcd(y, x % y); }

pair<ll, ll> euclid_extins(ll x, ll y) {
    pair<ll, ll> tmp;
    return x == 0
               ? make_pair(0ll, 1ll)
               : (tmp = euclid_extins(y % x, x), swap(tmp.first, tmp.second), tmp.first -= tmp.second * (y / x), tmp);
}

ll inv_mod(ll x, ll mod) { return (euclid_extins(mod, x).second % mod + mod) % mod; }

int nand(int x, int y) { return 1 - (x & y); }

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k;
    string s;
    cin >> n >> k >> s;
    k = n - k;

    int kk = (k - 5) / 2;

    k -= 2 * kk;

    vector<int> t(begin(s) + kk, end(s) - kk);
    for (auto& x : t) x -= '0';

    while (k--) {
        vector<int> u(t.size() - 1);
        for (int i = 0; i < u.size(); ++i) u[i] = nand(t[i], t[i + 1]);
        t = u;
    }
    for (int i = 0; i < t.size(); ++i) cout << t[i];
}