#include <iostream>
#include <vector>
#include <queue>
#define MAXN 5005
#define intt int
using namespace std ;
intt n , d[MAXN][MAXN] , t[MAXN][MAXN] , ans , mx , used[MAXN] ;
vector < intt > edge[MAXN] ;
queue < intt > q ;
int main () {
cin >> n ;
for ( int i = 0 ; i < n ; i ++ ) {
intt x , y ;
cin >> x >> y ;
edge[x].push_back ( y ) ;
edge[y].push_back ( x ) ;
}
for ( int i = 1 ; i <= n ; i ++ )
for ( int j = 1 ;j <= n ; j ++ ) d[i][j] = 5005 ;
for ( int i = 1 ; i <= n ; i ++ ) {
q.push ( i ) ;
d[i][i] = 0 ;
t[i][i] = 1 ;
while ( !q.empty ( ) ) {
intt v = q.front () ;
q.pop () ;
for ( int j = 0 ; j < edge[v].size () ; j ++ ) {
intt u = edge[v][j] ;
if ( d[i][u] >= d[i][v] + 1 ) {
if ( d[i][u] == d[i][v] + 1 ) t[i][u] += t[i][v] ;
else {
d[i][u] = d[i][v] + 1 ;
t[i][u] += t[i][v] ;
q.push ( u ) ;
}
}
}
}
for ( int j = 1 ; j <= n ; j ++ ) mx = max ( mx , d[i][j] ) ;
}
for ( int i = 1 ; i <= n ; i ++ ) {
for ( int j = i + 1 ; j <= n ; j ++ ) {
if ( d[i][j] == mx ) ans += t[i][j] ;
}
}
cout << ans << endl ;
return 0 ;
}
