#include <iostream>
#include <vector>
using namespace std;
vector<int> v[100005];
long long cnt[2];
void dfs(int node,int pnode,int color)
{
    cnt[color]++;
    for (int i=0;i<v[node].size();i++)
    {
        if (v[node][i]!=pnode)
        dfs(v[node][i],node,!color);
    }
}
int main()
{
    int n;
    scanf("%d",&n);
    for (int i=1;i<n;i++)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        v[a].push_back(b);
        v[b].push_back(a);
    }
    dfs(1,0,0);
    printf("%I64d",cnt[0]*cnt[1]-n+1);
}