import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop;


void main() {
    auto N = readln.chomp.to!int;
    auto A = N.iota.map!(_ => readln.split.map!(to!int).array).array;

    auto used = new bool[](N);
    auto tied = new int[](N);
    int point = 0;

    foreach (i; 0..N/2) {
        int x, y;
        do {
            x = uniform(0, N);
        } while (used[x]);
        used[x] = true;

        do {
            y = uniform(0, N);
        } while (used[y]);
        used[y] = true;

        tied[x] = y;
        tied[y] = x;
    }


    foreach (_; 0..5*10^^6) {
        int x, y;
        do {
            x = uniform(0, N);
            y = uniform(0, N);
        } while (x == y);


        int xx = tied[x];
        int yy = tied[y];
        if (A[x][xx] + A[y][yy] < A[x][y] + A[xx][yy]) {
            tied[x] = y;
            tied[y] = x;
            tied[xx] = yy;
            tied[yy] = xx;

        }
    }

    point = 0;
    fill(used, false);
    foreach (i; 0..N) {
        if (!used[i]) point += A[i][tied[i]];
        used[i] = used[tied[i]] = true;
    }

    point.writeln;
}