// Author: wlzhouzhuan
#include<bits/stdc++.h>
using namespace std;

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define ull unsigned long long
#define pii pair<int,int>
#define mset(s,t) memset(s,t,sizeof(s))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define SZ(x) ((int)x.size())
#define pb push_back
#define eb emplace_back
#define fir first
#define sec second

template<class T1,class T2>bool ckmax(T1 &a,T2 b){if(a<b)return a=b,1;else return 0;}
template<class T1,class T2>bool ckmin(T1 &a,T2 b){if(a>b)return a=b,1;else return 0;}

inline int read(){
    int x=0,f=0;char ch=getchar();
    while(!isdigit(ch))f|=ch=='-',ch=getchar();
    while(isdigit(ch))x=10*x+ch-'0',ch=getchar();
    return f?-x:x;
}
template<typename T>void print(T x){
    if(x<0)putchar('-'),x=-x;
    if(x>=10)print(x/10);
    putchar(x%10+'0');
}
template<typename T>void print(T x,char ch){
    print(x),putchar(ch);
}

const int N=100005;

#define u32 unsigned int

u32 ans;
int n;

namespace T1{
vector<int> adj[N];
int sum,sz[N],maxp[N],rt;
bool ban[N];
void getrt(int u,int fa){
    sz[u]=1,maxp[u]=0;
    for(auto v:adj[u]){
        if(v==fa||ban[v])continue;
        getrt(v,u),sz[u]+=sz[v],ckmax(maxp[u],sz[v]);
    }
    ckmax(maxp[u],sum-sz[u]);
    if(maxp[u]<maxp[rt])rt=u;
}
struct node{
    u32 cnt,sum1,sum2;
}f[N],g[N];
int Cdad[N];
unordered_map<int,u32> dep[N];
void dfs1(int u,int fa,int S){
    dep[S][u]=dep[S][fa]+1;
    for(auto v:adj[u]){
        if(v==fa||ban[v])continue;
        dfs1(v,u,S);
    }
}
void dfz(int u){
    ban[u]=1,dep[u][u]=0;
    for(auto v:adj[u]){
        if(ban[v])continue;
        dfs1(v,u,u);
    }
    for(auto v:adj[u]){
        if(ban[v])continue;
        sum=sz[v],rt=0,getrt(v,0);
        // printf("tree1 dfz %d -> %d\n",u,rt);
        Cdad[rt]=u,dfz(rt);
    }
}
void build(){
    rep(i,1,n-1){
        int u=read(),v=read();
        adj[u].pb(v),adj[v].pb(u);
    }
    sum=n,maxp[rt=0]=n,getrt(1,0);
    dfz(rt);
    // rep(i,1,n)printf("Cdad[%d]=%d\n",i,Cdad[i]);
}

void push(int u,int dlt,int extra){
    for(int i=u,j=0;i;j=i,i=Cdad[i]){
        u32 C=extra+dep[i][u];
        f[i].cnt+=dlt,f[i].sum1+=dlt*C,f[i].sum2+=dlt*C*C;
        if(j)g[j].cnt+=dlt,g[j].sum1+=dlt*C,g[j].sum2+=dlt*C*C;
    }
}
void query(int u,int extra){
    for(int i=u,j=0;i;j=i,i=Cdad[i]){
        u32 C=extra+dep[i][u];
        ans+=C*C*f[i].cnt+2u*C*f[i].sum1+f[i].sum2;
        if(j)ans-=C*C*g[j].cnt+2u*C*g[j].sum1+g[j].sum2;
    }
}
}

namespace T2{
vector<int> adj[N];
int sum,sz[N],maxp[N],rt;
bool ban[N];
void getrt(int u,int fa){
    sz[u]=1,maxp[u]=0;
    for(auto v:adj[u]){
        if(v==fa||ban[v])continue;
        getrt(v,u),sz[u]+=sz[v],ckmax(maxp[u],sz[v]);
    }
    ckmax(maxp[u],sum-sz[u]);
    if(maxp[u]<maxp[rt])rt=u;
}
int dep[N];
void dfs1(int u,int fa,int dlt){
    dep[u]=dep[fa]+1;
    T1::push(u,dlt,dep[u]);
    for(auto v:adj[u]){
        if(v==fa||ban[v])continue;
        dfs1(v,u,dlt);
    }
}
void dfs2(int u,int fa){
    dep[u]=dep[fa]+1;
    T1::query(u,dep[u]);
    for(auto v:adj[u]){
        if(v==fa||ban[v])continue;
        dfs2(v,u);
    }
}
void dfz(int u){
    // printf("now dfz u=%d\n",u);
    ban[u]=1,dep[u]=0;
    for(auto v:adj[u]){
        if(ban[v])continue;
        dfs2(v,u);
        dfs1(v,u,1);
        // printf("after v=%d,ans=%u\n",v,ans);
    }
    T1::query(u,0);
    // printf("add rt,ans=%u\n",ans);
    for(auto v:adj[u]){
        if(ban[v])continue;
        dfs1(v,u,-1);
    }

    for(auto v:adj[u]){
        if(ban[v])continue;
        sum=sz[v],rt=0,getrt(v,0);
        dfz(rt);
    }
}
void build(){
    rep(i,1,n-1){
        int u=read(),v=read();
        adj[u].pb(v),adj[v].pb(u);
    }
    sum=n,maxp[rt=0]=n,getrt(1,0);
    dfz(rt);
}
}

int main(){
    n=read(),T1::build(),T2::build();
    print(ans,'\n');
    return 0;
}