#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,ll>
#define fi first
#define in inline
#define se second
#define mp make_pair
#define pb push_back
const int N = 2e5+10;

ll read(){
	ll x = 0,f = 1;char c = getchar();
	for(;c < '0' || c > '9';c = getchar())if(c == '-')f = -1;
	for(;c >= '0' && c <= '9';c = getchar())x = (x<<1) + (x<<3) + c-'0';
	return x * f;
}

int n;
vector<int>e1[N],e2[N];


struct BIT{
	int c[N];
	int lowbit(int x){return x & (-x);}
	void add(int x,int val){
		for(;x <= n;x += lowbit(x))c[x] += val;
	}
	int ask(int x){
		int ans = 0;
		for(;x > 0;x -= lowbit(x))ans += c[x];
		return ans;
	}
	int ask(int l,int r){
		if(l > r)return 0;
		return ask(r) - ask(l - 1);
	}
}t;

int cnt1,cnt2;
int dfn1[N],dfn2[N],siz1[N],siz2[N],rnk1[N];
void dfs1(int x,int fa){
	dfn1[x] = ++cnt1,rnk1[cnt1] = x,siz1[x] = 1;
	for(int y : e1[x]){
		if(y == fa)continue;
		dfs1(y,x);
		siz1[x] += siz1[y];
	}
}
void dfs2(int x,int fa){
	dfn2[x] = ++cnt2,siz2[x] = 1;
	for(int y : e2[x]){
		if(y == fa)continue;
		dfs2(y,x);
		siz2[x] += siz2[y];
	}
}
vector<pair<pii,int> >G[N];

int main(){
	freopen("monkeyclim.in","r",stdin);
	freopen("monkeyclim.out","w",stdout);
	n = read();
	for(int i = 1;i < n;i++){
		int x = read(),y = read();
		e1[x].pb(y),e1[y].pb(x);
	}
	for(int i = 1;i < n;i++){
		int x = read(),y = read();
		e2[x].pb(y),e2[y].pb(x);
	}
	dfs1(1,0),dfs2(1,0);
	for(int i = 1;i <= n;i++){
		G[dfn1[i] - 1].pb({{dfn2[i],dfn2[i] + siz2[i] - 1},-1});
		G[dfn1[i] + siz1[i] - 1].pb({{dfn2[i],dfn2[i] + siz2[i] - 1},1});
	}
	ll ans = 0;
	for(int i = 1;i <= n;i++){
		t.add(dfn2[rnk1[i]],1);
		for(auto it : G[i])ans += (ll)t.ask(it.fi.fi,it.fi.se) * it.se;
	}
	printf("%lld\n",ans - n);

	return 0;

}