#include <bits/stdc++.h>
using namespace std;
int n;
std::vector<int> G[100005];
int color[100005];
void DFS(int s, int co) {
  color[s] = co;
  for (int i = 0; i < G[s].size(); i++) {
    int to = G[s][i];
    if (color[to] == 0) {
      DFS(to, -1 * co);
    }
  }
}
int main(int argc, char const *argv[]) {
  scanf("%d", &n);
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    G[u].push_back(v);
    G[v].push_back(u);
  }
  int s1 = 0;
  long long ans = 0;
  DFS(1, 1);
  for (int i = 1; i <= n; i++)
    if (color[i] == -1) s1++;
  printf("%lld\n", 1LL * (n - s1) * s1 - 1LL * n + 1LL);
  return 0;
}
