#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();
	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;
	}
	
	clock_t r0 = clock();
	int degree[n];
	memset(degree, 0, sizeof(degree));
	bool used[n];
	memset(used, 0, sizeof(used));
	for (int i = 0; i + 1 < n; i++) {
		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;
	static int que[2][1000000];
	static int head[2];
	que[0][head[0]++] = root;
	for (int i = 0; head[i & 1]; i++) {
		res += (int64_t) i * (i + 1) / 2 * head[i & 1];
		int next = (i ^ 1) & 1;
		head[next] = 0;
		for (int j = 0; j < head[i & 1]; j++) {
			memcpy(que[next] + head[next], &hen[que[i & 1][j]][0], sizeof(int) * hen[que[i & 1][j]].size());
			head[next] += hen[que[i & 1][j]].size();
		}
	}
	printf("%d\n", (int) (res % 1000000007));
	clock_t r1 = clock();
	fprintf(stderr, "took %f ms\n", (double)(r1 - r0) / CLOCKS_PER_SEC * 1000);
	return 0;
}