1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
#include<bits/stdc++.h>

using namespace std;
#define f first
#define s second
#define PB push_back
typedef long long ll;
typedef long double ld;
#define REP(x, y) for(int x=1;x<=(y);x++)
#define ROF(x, y) for(int x=(y);x>=0;x--)
#define FOR(x, z, y) for(int x=(z);x<=(y);x++)
#define INT(x) int x;scanf("%d",&x)
#define LL(x) ll x;scanf("%lld",&x)
#define CZ(x) char x;scanf(" %c",&x)
typedef pair<int, ll> pil;


int calc(int a,int b){
    return (a*(a+1))/2 - (b*(b-1))/2 - ((a-b+1)*(a-b))/2;
}


int main(){

        INT(n);
        INT(k);
        int wyn = 1e6;
        REP(i, n) {
            REP(j, i) {
                INT(x);
                //printf("%d %d %d\n", i, j, calc(i, j));
                if (x < wyn && calc(i, j) <= k)
                    wyn = x;
            }
        }
        printf("%d\n", wyn);

}