/*
 * O(n^3) solution checking each distance to see if it is greater than or equal to the
 * sum of two distances. Should be too slow on trees with small diameter.
 */

#include <iostream>
#include <vector>

using namespace std;

typedef long long ll;
typedef vector<ll> vi;
typedef vector<vi> vvi;

int main() {
    ll n;
    cin >> n;

    vvi adj_matrix(n, vi(n));
    for (ll i = 0; i < n; ++i) {
        for (ll j = 0; j < n; ++j) {
            cin >> adj_matrix[i][j];
        }
    }

    for (ll i = 0; i < n; ++i) {
        for (ll j = i+1; j < n; ++j) {
            bool success = true;
            for (ll k = 0; k < n; ++k) {
                if (k == i || k == j) continue;

                if (adj_matrix[i][j] >= adj_matrix[i][k] + adj_matrix[k][j]) {
                    success = false;
                    break;
                }
            }

            if (success) {
                cout << i+1 << " " << j+1 << endl;
            }
        }
    }
}