#include<bits/stdc++.h>
using namespace std;
pair<int,int>piramida[5000000];
#define st first
#define nd second
int main(){
int n,k;
cin>>n>>k;
int indeks=n*(n+1)/2;
int c=2;
int x;
cin>>x;
piramida[1]=make_pair(x,1);
if(k==1){
cout<<piramida[1].st;
return 0;
}
for(int i=1;i<indeks;i=i+c-1){
for(int a=i+1;a<=i+c;a++){
if(a==i+1){
cin>>x;
piramida[a]=make_pair(x,piramida[a-c+1].nd+1);
}
if(a==i+c){
cin>>x;
piramida[a]=make_pair(x,piramida[a-c].nd+1);
}
if(a>i+1&&a<i+c){
cin>>x;
piramida[a]=make_pair(x,piramida[a-c].nd+piramida[a-c+1].nd-piramida[a-c-c+2].nd+1);
}
}
c++;
}
int wynik=2020;
for(int i=1;i<indeks;i++){
if(piramida[i].nd<=k&&piramida[i].st<wynik){
wynik=piramida[i].st;
}
}
cout<<wynik;
return 0;
}