#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e5 + 10;
vector<int>adj[MAX];
int grau[MAX], vstd[MAX];
int cnt[2];
void dfs(int v, int g = 0) {
    grau[v] = g;
    vstd[v] = 1;
    cnt[g]++;
    for(auto u : adj[v]){
        if(!vstd[u]) {
            dfs(u, 1-g);
        }
    }
}
int main() {
    int n, u, v;
    scanf("%d", &n);
    memset(grau, -1, sizeof grau);
    for(int i = 0; i < n-1; ++i){
        scanf("%d %d", &u, &v);
        --u, --v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    dfs(0);
    long long ans = 0;
    for(int i = 0; i < n; ++i){
        if(grau[i] == 1){
            ans+= cnt[0] - adj[i].size();
        }
    }
    printf("%lld\n", ans);
    return 0;
}