#include <iostream>
#include <vector>
#include <cstring>
#include <fstream>
using namespace std;
typedef long long ll;
const int maxn = 1e5 + 10;
vector<int> graph[maxn];
const ll MOD = 1e9 + 7;
int painted[maxn];
ll dp[maxn][4];
void dfs(int node, int prev) {
    for(int i = 0; i < (int) graph[node].size(); i++) {
        int neighbour = graph[node][i];
        if(neighbour != prev) {
            dfs(neighbour, node);
        }
    }
    for(int current_color = 1; current_color <= 3; current_color++) {
        if(painted[node] != -1 and painted[node] != current_color) {
            continue;
        }
        
        dp[node][current_color] = 1;
        
        for(int i = 0; i < (int) graph[node].size(); i++) {
            int neighbour = graph[node][i];
            if(neighbour != prev) {
                ll sum = 0;
                for(int next_color = 1; next_color <= 3; next_color++) {
                    if(current_color != next_color) {
                        sum += dp[neighbour][next_color];
                    }
                }
                dp[node][current_color] *= sum;
                dp[node][current_color] %= MOD;
                
            }
        }
    }
}
int main(int argc, const char * argv[]) {
    ios_base::sync_with_stdio(false);
    ifstream cin("barnpainting.in");
    ofstream cout("barnpainting.out");
    int n, k;
    cin >> n >> k;
    
    for(int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    memset(painted, -1, sizeof painted);
    for(int i = 0; i < k; i++) {
        int a, b;
        cin >> a >> b;
        a--;
        painted[a] = b;
    }
    dfs(0, -1);
    cout << (dp[0][1] + dp[0][2] + dp[0][3]) % MOD  << endl;
    return 0;
}