#include <stdio.h>
#include <stdlib.h>

int maxScore = 0;
int edges[1000][2];
int edgeCount = 0;

void swap(int* a, int* b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

void permute(int* values, int n, int start) {
    if (start == n - 1) {
        int score = 0;
        for (int i = 0; i < edgeCount; i++) {
            score += values[edges[i][0]] * values[edges[i][1]];
        }
        if (score > maxScore) {
            maxScore = score;
        }
        return;
    }
    
    for (int i = start; i < n; i++) {
        swap(&values[start], &values[i]);
        permute(values, n, start + 1);
        swap(&values[start], &values[i]);
    }
}

int maximumScore(int n) {
    int* values = (int*)malloc(n * sizeof(int));
    for (int i = 0; i < n; i++) {
        values[i] = i + 1;
    }
    maxScore = 0;
    permute(values, n, 0);
    free(values);
    return maxScore;
}

int main() {
    int n;
    scanf("%d", &n);
    
    int a, b;
    while (scanf("%d %d", &a, &b) == 2) {
        edges[edgeCount][0] = a;
        edges[edgeCount][1] = b;
        edgeCount++;
    }
    
    printf("%d\n", maximumScore(n));
    return 0;
}