#include <bits/stdc++.h>
using namespace std;
#include<atcoder/all>
// using mint = atcoder::modint998244353;
using ld = long double;
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(int)(n);++i)
template<typename T>bool chmin(T&a,T b){return b<a?(a=b,1):0;}
template<typename T>bool chmax(T&a,T b){return b>a?(a=b,1):0;}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int N;
    cin>>N;
    vector<pair<int,int>> e1,e2;
    rep(i,N-1){
        int a,b;
        cin>>a>>b;
        a--;b--;
        e1.push_back({a,b});
        e1.push_back({b,a});
    }
    rep(i,N-1){
        int a,b;
        cin>>a>>b;
        a--;b--;
        e2.push_back({a,b});
        e2.push_back({b,a});
    }
    atcoder::internal::csr<int> g1(N, e1);
    atcoder::internal::csr<int> g2(N, e2);
    
    vector<int> D1(N),D2(N);
    auto dfs1=[&](auto dfs1, int v, int p, int d)->void {
        D1[v]=d;
        for(int i=g1.start[v];i<g1.start[v+1];i++){
            int e=g1.elist[i];
            if(e==p) continue;
            dfs1(dfs1, e, v, d+1);
        }
    };
    auto dfs2=[&](auto dfs2, int v, int p, int d)->void {
        D2[v]=d;
        for(int i=g2.start[v];i<g2.start[v+1];i++){
            int e=g2.elist[i];
            if(e==p) continue;
            dfs2(dfs2, e, v, d+1);
        }
    };

    unsigned long ans=0;
    rep(i,N){
        dfs1(dfs1, i, -1, 0);
        dfs2(dfs2, i, -1, 0);
        rep(j,N){
            ans+=D1[j]*D2[j];
        }
    }
    cout<<ans<<"\n";
}