#pragma GCC optimize("O3")
#include<bits/stdc++.h> 
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
//const ll mod=998244353;
const ll mod=1000000007;
const vector<int> dy={-1,0,1,0},dx={0,-1,0,1};
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(20);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T>void debag(const vector<T> &a){cerr<<"debag :";for(auto v:a)cerr<<v<<" ";cerr<<"\n";}
template<class T>void print(const vector<T> &a){for(auto v:a)cout<<v<<" ";cout<<"\n";}
V<ll> a,b;
ll n,k;
bool ok(ll m){
      V<ll> cb;
      for(int i=0;i<k;i++)if(b[k-i-1]>=m)cb.emplace_back(i+1);
      if(cb.size()==0)return false;
      int  siz=cb.back();
      V<ll> dp(siz,2*inf);
      for(ll i=0;i<k;i++){
           if(a[i]>=m){
                for(int c:cb)if(i+c>=k)chmin(dp[(i+c)%siz],i+c);
           }
      }
      priority_queue<P,V<P>,greater<P>> pq;
      for(int i=0;i<siz;i++){
            pq.emplace(dp[i],i);
      }
      while(pq.size()){
             auto [v,cur]=pq.top();
             pq.pop();
             if(dp[cur]!=v)continue;
             if(v>n)return false;
             if(n%siz==cur)return true;
             for(ll c:cb){
                    if(v+c>=k&&chmin(dp[(v+c)%siz],v+c)){
                           pq.emplace(dp[(v+c)%siz],(v+c)%siz);
                    }
             }
      }
      return false;
}
int main(){
     cin>>k>>n;
     a.resize(k);b.resize(k);
     for(int i=0;i<k;i++)cin>>a[i];
     for(int i=0;i<k;i++)cin>>b[i];
     V<ll> cp=a;
     for(int i=0;i<k;i++)cp.emplace_back(b[i]);
     sort(all(cp));
     if(n<k){
           cout<<a[n]<<"\n";
           return 0;
     }
     int l=0,r=2*k;
     while(r-l>1){
            int mid=(l+r)/2;
            if(ok(cp[mid]))l=mid;
            else r=mid;
     }
     cout<<cp[l]<<"\n";
}