#include <bits/stdc++.h>
#define FOR( i, x, n, d ) for( int i = x; i <= n; i += d )
using namespace std;
const int N = 3e5;
int a[N], b[N], x[N], y[N];
long long ans = 0;
int main()
{
// freopen("triangle.in", "r", stdin);
// freopen("triangle.out", "w", stdout);
int n; cin >> n;
FOR( i, 1, n, 1 )
{
cin >> x[i] >> y[i];
b[y[i]] ++;
}
FOR( i, 1, n, 1 )
{
ans += a[x[i]] * 1ll * b[y[i]];
a[x[i]] += b[y[i]];
}
cout << ans / 2;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
348 KB |
Output is correct |
4 |
Incorrect |
0 ms |
348 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |