n = int(input())
tree = {}
node_count_edges = {}
u, v = map(int, input().split())
tree[u] = [v]
tree[v] = [u]
root = u
for i in range(n - 2):
u, v = map(int, input().split())
if u not in tree: tree[u] = []
if v not in tree: tree[v] = []
tree[u].append(v)
tree[v].append(u)
curr_nodes = [root]
l = 0
r = 0
i = 0
node_side = {}
passed = set()
while len(curr_nodes) != 0:
new_curr_nodes = []
for node in curr_nodes:
if node in passed:
continue
passed.add(node)
new_curr_nodes.extend(tree[node])
if i % 2 == 0:
node_side[node] = 'left'
else:
node_side[node] = 'right'
if i % 2 == 0:
l += 1
else:
r += 1
i += 1
curr_nodes = new_curr_nodes
ans = 0
for node in tree:
if node_side[node] == 'left':
ans += r - len(tree[node])
else:
ans += l - len(tree[node])
print(ans // 2)/*亲爱的上帝，我求你给我力量来赢得这场战斗。*/
#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define vl vector<i64>
#define vi vector<int>
template<typename T> bool chkmin(T &a, T b){return (b < a) ? a = b, 1 : 0;}
template<typename T> bool chkmax(T &a, T b){return (b > a) ? a = b, 1 : 0;}
constexpr int mxN = 2e5;
vector<vector<int>> A(mxN);
vector<bool> vis(mxN), color(mxN, 0);
void solve() {
int N;
cin >> N;
for(int i=0; i<N-1; i++) {
int u, v;
cin >> u >> v;
A[--u].push_back(--v);
A[v].push_back(u);
}
i64 ONE = 0;
function<void(int, int)> dfs = [&](int x, int col) {
vis[x] = 1;
color[x] = col;
if(color[x]) ONE++;
for(int j:A[x]) {
if(!vis[j]) {
dfs(j, col ^ 1);
}
}
};
for(int i=0; i<N; i++) {
if(!vis[i]) {
dfs(i, 1);
}
}
cout << ONE *1LL* (N - ONE) - N + 1;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int TT=1;
// cin >> TT;
while(TT--){
solve();
}
} 1302. Deepest Leaves Sum | 1209. Remove All Adjacent Duplicates in String II |
994. Rotting Oranges | 983. Minimum Cost For Tickets |
973. K Closest Points to Origin | 969. Pancake Sorting |
967. Numbers With Same Consecutive Differences | 957. Prison Cells After N Days |
946. Validate Stack Sequences | 921. Minimum Add to Make Parentheses Valid |
881. Boats to Save People | 497. Random Point in Non-overlapping Rectangles |
528. Random Pick with Weight | 470. Implement Rand10() Using Rand7() |
866. Prime Palindrome | 1516A - Tit for Tat |
622. Design Circular Queue | 814. Binary Tree Pruning |
791. Custom Sort String | 787. Cheapest Flights Within K Stops |
779. K-th Symbol in Grammar | 701. Insert into a Binary Search Tree |
429. N-ary Tree Level Order Traversal | 739. Daily Temperatures |
647. Palindromic Substrings | 583. Delete Operation for Two Strings |
518. Coin Change 2 | 516. Longest Palindromic Subsequence |
468. Validate IP Address | 450. Delete Node in a BST |