#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>

using namespace std;
int n, m;
vector<int> used;
vector<vector<int>> graf;
vector<int> first;
vector<int> second;

bool dfs(int v, int color)
{
    if (color == 1)
        first.push_back(v);
    if (color == 2)
        second.push_back(v);
    used[v] = color;
    for (int u: graf[v])
    {
        if (used[u] == 0)
            if (!dfs(u, 3- color))
                    return false;
            else if (used[u] == color)
                    return false;
    }
    return true;
}



int main()
{
    cin >> n;
    used.resize(n, 0);
    graf.resize(n);
    for (int i = 0; i < n - 1; ++i)
    {
        int a, b;
        cin >> a >> b;
        graf[a - 1].push_back(b - 1);
        graf[b - 1].push_back(a - 1);

    }
    dfs(0,1);
    int ans = 0;
    int ans2 = 0;
    for (int elem: first)
    {
        ans += second.size() - graf[elem].size();
    }
    cout << ans;





}