#include <cstdio>
#include <array>
#include <cassert>
#define repeat(i,n) for (int i = 0; (i) < int(n); ++(i))
#define repeat_from(i,m,n) for (int i = (m); (i) < int(n); ++(i))
using namespace std;
template <class T> inline void setmax(T & a, T const & b) { a = max(a, b); }

constexpr int max_n = 24;
int n;
array<array<int, max_n>, max_n> f;
array<bool, max_n> used;
int result = 0;
int upper_bound(int i, int score) {
    repeat_from (j, i, n) if (not used[j]) {
        int acc = 0;
        repeat_from (k, i, n) if (not used[k]) {
            setmax(acc, f[j][k]);
        }
        score += (acc + 1) / 2;
    }
    return score;
}
void go(int i, int score) {
    if (i == n) {
        setmax(result, score);
        return;
    }
    if (used[i]) {
        go(i+1, score);
        return;
    }
    if (upper_bound(i, score) <= result) {
        return;
    }
    repeat_from (j, i+1, n) if (not used[j]) {
        used[j] = true;
        go(i+1, score + f[i][j]);
        used[j] = false;
    }
}
int main() {
    scanf("%d", &n);
    assert (n <= max_n);
    repeat (y, n) repeat (x, n) scanf("%d", &f[y][x]);
    go(0, 0);
    printf("%d\n", result);
    return 0;
}