package chelper;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import io.InputReader;
import io.OutputWriter;
import misc.SimpleSavingChelperSolution;


public class B extends SimpleSavingChelperSolution {

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    wrapSolve(testNumber, in, out);
  }

  int n;
  List<List<Integer>> edges;
  long c1 = 0;
  long c2 = 0;
  Set<Integer> visited;

  @Override
  public void solve(int testNumber) {
    n = in.nextInt();

    edges = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      edges.add(new ArrayList<>());
    }


    for (int i = 0; i < n - 1; i++) {
      int a = in.nextInt() - 1;
      int b = in.nextInt() - 1;

      edges.get(a).add(b);
      edges.get(b).add(a);
    }

    visited = new HashSet<>();
    dfs(0, true);

    long total = c1 * c2 - (n - 1);
    out.println(total);
  }

  void dfs(int v, boolean color) {
    visited.add(v);
    if (color) {
      c1++;
    } else {
      c2++;
    }

    for (Integer o : edges.get(v)) {
      if (visited.contains(o)) {
        continue;
      }
      dfs(o, !color);
    }
  }
}