1 #include <bits/stdc++.h>

 2 using namespace std;

 3 typedef long long ll;

 4 const int maxn = 2e5 + 10;

 5 const ll mod = 998244353;

 6 vector<int> mp[maxn];

 7 ll ans = 0, cnt[3];

 8 int n;

 9 ll dfs(int u, int pre,int now) {

10     ++cnt[now];

11     ll siz = 1;

12     for(int i = 0; i < mp[u].size(); ++i) {

13         int v = mp[u][i];

14         if(v == pre) continue;

15         siz += dfs(v, u, now^1);

16     }

17     ans += siz * (n - siz);

18     return siz;

19 }

20 int main() {

21

22

23     scanf("%d", &n);

24     int u, v;

25     for(int i = 1; i < n; ++i) {

26         scanf("%d %d", &u, &v);

27         mp[u].push_back(v);

28         mp[v].push_back(u);

29     }

30     dfs(1,0,0);

31     printf("%lld\n", (ans + cnt[0] * cnt[1]) / 2);

32     return 0;

33 }