#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<algorithm>

#include<cctype>

#include<cmath>

#include<cstdlib>

#include<queue>

#include<ctime>

#include<vector>

#include<set>

#include<map>

#include<stack>

using namespace std;

int n,L,R,num,Max,cnt,col[],d[],sum[],du[];

long long Ans;

vector<int>high[],low[];

inline void build(int le,int ri,int wh){

    sum[wh]=;

    d[wh]=ri;

    if(le==ri)return;

    int mid=(le+ri)>>;

    build(le,mid,wh<<);

    build(mid+,ri,wh<<|);

}

inline void pd(int wh){

    if(col[wh]){

      d[wh<<]+=col[wh];

      col[wh<<]+=col[wh];

      d[wh<<|]+=col[wh];

      col[wh<<|]+=col[wh];

      col[wh]=;

    }

}

inline void up(int wh){

    d[wh]=max(d[wh<<],d[wh<<|]);

    sum[wh]=(d[wh<<]==d[wh]?sum[wh<<]:)+(d[wh<<|]==d[wh]?sum[wh<<|]:);

}

inline void update(int le,int ri,int wh,int x,int y){

    if(le>=x&&ri<=y){

      col[wh]++;

      d[wh]++;

      return;

    }

    pd(wh);

    int mid=(le+ri)>>;

    if(mid>=x)update(le,mid,wh<<,x,y);

    if(mid<y)update(mid+,ri,wh<<|,x,y);

    up(wh);

}

inline void que(int le,int ri,int wh,int x,int y){

    if(le>=x&&ri<=y){

      if(d[wh]>Max)Max=d[wh],cnt=sum[wh];

        else if(d[wh]==Max)cnt+=sum[wh];

      return;

    }

    pd(wh);

    int mid=(le+ri)>>;

    if(mid>=x)que(le,mid,wh<<,x,y);

    if(mid<y)que(mid+,ri,wh<<|,x,y);

    up(wh);

}

inline void add(int x){

    for(int i=;i<low[x].size();i++){

      update(,n,,,low[x][i]);

      if(low[x][i]>=L)num+=((++du[x])==)+((++du[low[x][i]])==);

    }

}

inline void deal(int x){

    for(int i=;i<high[x].size();i++){

      if(high[x][i]<=R)num-=((--du[x])==)+((--du[high[x][i]])==);

    }

}

int main(){

    int i,j,k;

    scanf("%d",&n);

    for(i=;i<n;i++){

      int x,y;

      scanf("%d%d",&x,&y);

      if(x>y)swap(x,y);

      high[x].push_back(y);

      low[y].push_back(x);

    }

    L=;

    build(,n,);

    for(i=;i<=n;i++){

      R=i;

      add(i);

      while(num)deal(L),L++;

      Max=;

      que(,n,,L,i);

      if(Max==i)Ans+=1ll*cnt;

    }

    cout<<Ans;

    return ;

}