#include <bits/stdc++.h>

struct FastIO {
	char buf[20000000];
	char *ptr = buf;
	void read() {
		int size;
		size = fread(buf, 1, sizeof(buf) - 1, stdin);
		buf[size] = '\0';
		ptr = buf;
	}
	FastIO () {
		read();
	}
	void inc() {
		ptr++;
		// if (++ptr == buf + sizeof(buf) || !*ptr) read();
	}
	template<typename Integer> Integer read() {
		bool neg = false;
		Integer res = 0;
		while ((*ptr < '0' || *ptr > '9') && *ptr != '-') inc();
		if (*ptr == '-') neg = true, inc();
		while (*ptr >= '0' && *ptr <= '9') res = res * 10 + *ptr - '0', inc();
		return neg ? -res : res;
	}
} fastio;
#define ri fastio.read<int>
#define rs64 fastio.read<int64_t>


std::vector<std::vector<int> > hen;

int main() {
	int n = ri();
	int degree[n];
	memset(degree, 0, sizeof(degree));
	bool used[n];
	memset(used, 0, sizeof(used));
	std::pair<int, int> hens[n - 1];
	for (int i = 0; i + 1 < n; i++) {
		hens[i].first = ri() - 1;
		hens[i].second = ri() - 1;
		degree[hens[i].first]++;
		used[hens[i].second] = true;
	}
	
	int root = std::find(used, used + n, 0) - used;
	hen.resize(n);
	for (int i = 0; i < n; i++) hen[i].resize(degree[i]);
	for (auto i : hens) hen[i.first][--degree[i.first]] = i.second;
	
	int64_t res = 0;
	std::vector<int> cur, next;
	cur.reserve(n);
	next.reserve(n);
	cur.push_back(root);
	for (int i = 0; cur.size(); i++) {
		res += (int64_t) i * (i + 1) / 2 * cur.size();
		next.clear();
		for (auto j : cur) next.insert(next.end(), hen[j].begin(), hen[j].end());
		std::swap(cur, next);
	}
	printf("%d\n", (int) (res % 1000000007));
	return 0;
}