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
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<vector>

using namespace std;

typedef vector<int> VI;
typedef long long LL;

#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 VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define PB push_back
#define ST first
#define ND second

class Solver {
    private:
    int n, k;
    vector<VI> wines;

    public:
    
    void readInput() {
        cin >> n >> k;
        wines.resize(n, VI(n));
        REP(i, n) {
            REP(j, i+1) {
                cin >> wines[i][j];
            }
        }
    }

    void solve() {
        int best = wines[0][0];
        REP(row, n) {
            int i = 0, j = row;
            int count = row + 1;
            int diff = row - 1;
            while(i <= j && count <= k) {
                if(wines[row][i] < best) { best = wines[row][i]; }
                if(wines[row][j] < best) { best = wines[row][j]; }
                i++; j--;
                count += diff;
                diff -= 2;
            }
        }
        cout << best << '\n';
    }
};

int main() {
	ios_base::sync_with_stdio(0);
    Solver solver;
    solver.readInput();
    solver.solve();
    return 0;
}