#include<bits/stdc++.h>
#define endl '\n'
#define int long long
#define unmap unordered_map
#define unset unordered_set
#define MAXQ priority_queue
#define rep(i,a,b) for(int i=a;i<=(b);++i)
#define frep(i,a,b) for(int i=a;i<(b);++i)
using namespace std;
template<typename T> using MINQ=priority_queue<T,vector<T>,greater<T> >;
using pii=pair<int,int>;
using vi=vector<int>;
using vii=vector<vi>;
const int MAXN = 200010;
int n,cnt[MAXN],deg[MAXN];
int vis[MAXN];
vector<int> nxt[MAXN];
int point;
bool flag;
vector<int> g;
void dfs(int p, int fa) {
    if(vis[p]) {
        point = p;
        flag = true;
        return;
    }
    vis[p] = true;
    for(auto x : nxt[p]) {
        if(x == fa) continue;
        dfs(x, p);
        if(flag) {
            g.push_back(p);
            if(p == point) {
                flag = false;
            }
            return;
        }
    }
    vis[p] = false;
    return;
}
void add(int i) {
    cerr<<"add"<<i<<" "<<deg[i]<<endl;
    cnt[deg[i]]--;
    deg[i]++;
    cnt[deg[i]]++;
}
void del(int i) {
    cerr<<"del"<<i<<" "<<deg[i]<<endl;

    cnt[deg[i]]--;
    deg[i]--;
    cnt[deg[i]]++;
}
void solve(){
    int n;
    cin >> n;
    rep(i, 1, n) {
        int x, y;
        cin >> x >> y;
        nxt[x].push_back(y);
        nxt[y].push_back(x);
    }
    dfs(1, 0);
    // for(auto x : g) cout << x << " ";
    // cout<<endl;
    for(int i=1;i<=n;i++) {
        deg[i]=nxt[i].size();
        cnt[nxt[i].size()]++;
    }
    int ans=0;
    for(int i=0;i<g.size();i++) {
        int u=g[i],v=g[(i+1)%g.size()];

        del(u);del(v);
        for(int j=1;j<=n;j++) cerr<<cnt[j]<<" ";
        cerr<<endl;
        if(cnt[1]+cnt[2]+cnt[3]+cnt[4]==n) {
            ans+=cnt[1]+cnt[2]+cnt[3];
        }
        // cerr<<cnt[1]+cnt[2]+cnt[2]+cnt[3]+cnt[4]<<endl;
        add(u);add(v);
    }
    cout<<ans<<endl;
}
signed main(){
    ios::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
    int _t=1;
    //	cin>>_t;
    //	cout<<fixed<<setprecision(20);
    for(int i=1;i<=_t;i++){
        //cout<<"Case "<<i<<": ";
        solve();
    }
    return 0;
}
/*
6
1 2
1 3
1 4
1 5
1 6
2 3
*/