3593.cpp

#include <iostream>
#include <cmath>
#include <cstdio>
#include <vector>

using namespace std;

typedef vector<int> vi;
typedef long long int lli;

int main(){

    lli n, t1, t2, m[7][7], c[40001], ans;
    cin >> n;
    for (int i = 0; i < 7; i++)
        for (int j = 0; j < 7; j++)
            m[i][j] = 0;
    for (int i = 0; i < n; i++){
        cin >> t1 >> t2;
        if (t1 > t2)
            swap(t1, t2);
        m[t1][t2]++;
    }
    c[0] = 0;
    for (int i = 1; i <= n; i++)
        c[i] = c[i - 1] - 1 + i;
    ans = 0;
    for (int i = 0; i <= 6; i++)
        for (int j = 0; j <= 6; j++){
            if (m[i][j] == 0)
                continue;
            ans += c[m[i][j]];
            for (int k = j + 1; k <= 6; k++)
                if (m[i][k])
                    ans += m[i][k] * m[i][j];
            for (int k = i + 1; k <= 6; k++)
                if (m[k][j])
                    ans += m[k][j] * m[i][j];
        }

    cout << ans << endl;

    return 0;
}