#include<bits/stdc++.h>
using namespace std;
using ll=long long;
constexpr ll INF=(ll)(1e18)+1;
bool chmin(ll&a,ll b){return a>b?a=b,true:false;}
int K;
ll N,A[10005],B[10005];
bool check(ll X){
    vector<int>b;
    for(int i=K-1;i>=0;i--){
        if(B[i]>=X)b.push_back(K-i);
    }
    if(b.size()==0)return N<K && A[N]>=X;
    int M=b[0];
    vector<ll>dist(K+M,INF);
    vector<bool>seen(K+M,false);
    for(int i=0;i<K;i++){
      if(A[i]>=X)dist[i]=i;
    }
    for(int i=0;i<K+M;i++){
        int idx=-1;
        ll mn=INF+1;
        for(int j=0;j<K+M;j++){
            if(!seen[j] && chmin(mn,dist[j]))idx=j;
        }
        seen[idx]=true;
        for(int j:b){
            if(idx<K){
                if(idx+j>=K)chmin(dist[K+(idx+j)%M],dist[idx]+j);
            }else{
                chmin(dist[K+(idx-K+j)%M],dist[idx]+j);
            }
        }
    }
    if(N<K)return dist[N]<=N;
    else return dist[K+N%M]<=N;
}
int main(){
    cin>>K>>N;
    for(int i=0;i<K;i++)cin>>A[i];
    for(int i=0;i<K;i++)cin>>B[i];
    ll ok=-INF,ng=INF;
    while(ng-ok>1){
        ll mid=(ok+ng)/2;
        if(check(mid))ok=mid;
        else ng=mid;
    }
    cout<<ok<<endl;
}