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//Tadrion
#include <cstdio>
#include <vector>
#include <iostream>
#include <deque>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <algorithm>
#include <utility>
using namespace std;
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define CLEAR(x) (memset(x,0,sizeof(x)))
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(),(x).end()
#define VAR(v, n) __typeof(n) v = (n)
#define FOR(x, b, e) for(int x = b; x <= (e); ++x)
#define FORD(x, b, e) for(int x = b; x >= (e); --x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define FOREACH(i, c) for(VAR(i,(c).begin()); i != (c).end(); ++i)
#define DBG(v) cout<<#v<<" = "<<v<<endl;
#define IN(x,y) ((y).find(x)!=(y).end())
#define ST first
#define ND second
#define PB push_back
#define PF push_front
#define MP make_pair
#define TTT 2010
typedef long long int LL;
typedef pair<int,int> PII;
typedef vector<int> VI;
long long int t[TTT][TTT];
int r[TTT][TTT];
int minn = 2020;

int calc(int i, int j)
{
  //if (j == i) return i;
  return j*(i-j+1);
}

int n,k;

int main() {
  cin >> n >> k;
  int a;
  for (int i = 1; i <= n; i++)
    {
      for (int j = 1; j <= i; j++)
      {
        cin >> a;
        if (calc(i,j) <= k) minn = MIN(minn, a);
      }
    }
  cout << minn << endl;
  return 0;
}