#include <iostream>
#include <vector>
#include <cmath>
#include <set>
#include <string>

int many(int r, int c)
{
    return (r-c+1)*c;
}

int main()
{
    int oldest = 2020;
    int n,k;
    
    std::cin >> n >> k;
    int tmp;
    for (int i = 1;i<=n;++i)
    {
        for (int j = 1; j<=i;++j)
        {
            std::cin >> tmp;
            if (many(i,j)<=k && tmp < oldest)
                oldest = tmp;
        }
    }
    std::cout << oldest << std::endl;
    return 0;
}