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#include <bits/stdc++.h>

using namespace std;

int n,k,x;
int max_k=2;


int minimals[2002000];

int main(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    for(int i = 0; i<2002000; i++) minimals[i]=INT_MAX;
    cin>>n>>k;

    cin>>x;
    minimals[1]=min(minimals[1],x);
    cin>>x;
    minimals[2]=min(minimals[2],x);
    cin>>x;
    minimals[2]=min(minimals[2],x);

    for(int i = 3; i<=n; i++){
        if(i%2==1)
        {

            int add_p=((i/2) - 1)*2 + 1;
            int add_res=add_p;

            cin>>x;
            max_k=max(max_k,i);
            minimals[i]=min(minimals[i],x);

            for(int j = 2; j<=i/2; j++){
                cin>>x;
                max_k=max(max_k,i+add_res);
                minimals[i+add_res]=min(minimals[i+add_res],x);
                add_p-=2;
                add_res+=add_p;
            }

            cin>>x;
            max_k=max(max_k,i+add_res);
            minimals[i+add_res]=min(minimals[i+add_res],x);

            add_res--;
            add_p=3;
            for(int j = i/2 + 2; j<=i; j++){
                cin>>x;
                max_k=max(max_k,i+add_res);
                minimals[i+add_res]=min(minimals[i+add_res],x);
                add_res-=add_p;
                add_p+=2;
            }

        }
        else  //even
        {

            int add_p=((i/2) - 1)*2;
            int add_res=add_p;

            cin>>x;
            max_k=max(max_k,i);
            minimals[i]=min(minimals[i],x);

            for(int j = 2; j<=i/2; j++){
                cin>>x;
                max_k=max(max_k,i+add_res);
                minimals[i+add_res]=min(minimals[i+add_res],x);
                add_p-=2;
                add_res+=add_p;
            }

            //add_res--;
            add_p=2;
            for(int j = i/2 + 1; j<=i; j++){
                cin>>x;
                max_k=max(max_k,i+add_res);
                minimals[i+add_res]=min(minimals[i+add_res],x);
                add_res-=add_p;
                add_p+=2;
            }

        }
    }


    /*
    for(int i = 1 ; i<=max_k; i++){
        cout<<minimals[i]<<endl;
    }*/

    for(int i = 1 ; i<=n*(n+1)*0.5; i++){
        minimals[i]=min(minimals[i],minimals[i-1]);
        //cout<<i<<" "<<minimals[i]<<endl;
    }

    cout<<minimals[k];

}