#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

deque<char> get(deque<char> x){
	deque<char> ret;
	rep(i,x.size()-1){
		int a = x[i] - '0';
		int b = x[i+1] - '0';
		a &= b;
		a ^= 1;
		ret.push_back('0' + a);
	}
	return ret;
}

int main() {
	
	int N,K;
	cin>>N>>K;
	
	string s;
	cin>>s;
	
	deque<char> ans;
	rep(i,s.size()){
		ans.push_back(s[i]);
	}
	int cur = N;
	cur--;
	ans = get(ans);
	
	while(cur!=K){
		if(cur-2 >= K){
			ans.pop_front();
			ans.pop_back();
			cur -= 2;
		}
		else{
			ans = get(ans);
			cur--;
		}
	}
	
	rep(i,K){
		cout<<ans[i];
	}
	cout<<endl;
	
    return 0;
}