#include <iostream>
#include <vector>
#include <cstring>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e5 + 10;
const ll MOD = 1e9 + 7;
int n, k;
vector<int> graph[maxn];
int already_colored[maxn];
ll dp[maxn][5];
void dfs(int node, int prev) {
    //cout << node << endl;
    for(int i = 0; i < graph[node].size(); i++) {
        int sosed = graph[node][i];
        if(sosed == prev) continue;
        dfs(sosed, node);
    }
    for(int color = 1; color <= 3; color++) {
        if(already_colored[node] != color and already_colored[node] != -1) continue;
            dp[node][color] = 1;

        for(int i = 0; i < graph[node].size(); i++) {
            int sosed = graph[node][i];
            if(sosed == prev) continue;
            
            ll sum = 0;
            for(int next_color = 1; next_color <= 3; next_color++) {
                if(color == next_color) continue;
                sum += dp[sosed][next_color];
                sum %= MOD;
            }
            // cout << sum << endl;
            dp[node][color] *= sum;
            dp[node][color] %= MOD;
            
        }
    }
}
int main() {
    ifstream cin("barnpainting.in");
    ofstream cout("barnpainting.out");
    cin >> n >> k;
    for(int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    memset(already_colored, -1, sizeof already_colored);
    for(int i = 0; i < k; i++) {
        int b, c;
        cin >> b >> c;
        already_colored[b] = c;
    }
    dfs(1, -1);
  
  cout << (dp[1][1] + dp[1][2] + dp[1][3]) % MOD << endl;
    return 0;
}