#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

ll ans = 0;

struct Graph {
    struct Vertex { int n; };
    struct Edge { int i, n; };
    Graph(int n, int m) : v(n, { -1 }), e(m), n(n), m(0) {}
    void add_edge(int i, int j) {
        e[m] = { j, v[i].n };
        v[i].n = m;
        m++;
    }
    void dfs(int i, int d) {
        for (int j = v[i].n; j >= 0; j = e[j].n) {
            Edge& o = e[j];
            dfs(o.i, d + 1);
        }
        ans += (ll)d * (d + 1) / 2;
    }
    vector<Vertex> v;
    vector<Edge> e;
    int n, m;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;

    Graph g(n, (n - 1) * 2);
    int x = 0;

    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;

        g.add_edge(a, b);
        x ^= b;
    }
    for (int i = n & ~3; i < n; i++) {
        x ^= i;
    }

    g.dfs(x, 0);

    cout << ans % 1000000007 << endl;

    return 0;
}