#include<bits/stdc++.h>
#define int long long
#define mod 998244353ll
#define pii pair<int,int>
#define fi first
#define se second
#define mems(x,y) memset(x,y,sizeof(x))
#define pb push_back
using namespace std;
const int maxn=100010;
const int inf=1e18;
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch-48);ch=getchar();}
	return x*f;
}
bool Mbe;

int n,k;
int a[maxn];
char s[maxn];
bool check(int x){
	int cnt=0;
	for(int i=1;i<=n;i++)if(a[i]>=x){
		if(s[i]=='0')cnt=0;
		else{
			++cnt;
			if(cnt>=k)return 1;
		}
	}
	return 0;
}
void work(){
	n=read();k=read();
	for(int i=1;i<=n;i++)a[i]=read();
	scanf("%s",s+1);
	int l=1,r=maxn-10,res=0;
	while(l<=r){
		int mid=l+r>>1;
		if(check(mid))l=mid+1,res=mid;
		else r=mid-1;
	}
	printf("%lld\n",res);
}

// \
444

bool Med;
int T;
signed main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	
//	ios::sync_with_stdio(0);
//	cin.tie(0);cout.tie(0);
	
//	cerr<<(&Mbe-&Med)/1048576.0<<" MB\n";
	
	T=1;
	while(T--)work();
}