#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
#define int long long
const int N = 1e6 + 5, mod = 1e9 + 7;

int val[N];
vector<int>tree[N];

int ans;
void dfs(int step, int u, int fa){
    ans ^= val[u];
    //cout << val[u] << ' ';
    //cout << ans << ' ';
    if(step == 2) return;
    for(auto v : tree[u]){
        if(v == fa) continue;
        //cout << ans << ' ';
        dfs(step + 1, v, u);
    }
}

void solve(){
    int n, q;
    cin >> n >> q;
    for(int i = 1; i <= n; i++) cin >> val[i];
    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        tree[u].push_back(v);
        tree[v].push_back(u);
    }
    int res = 0;
    for(int i = 1; i <= q; i++){
        ans = 0;
        int u, x;
        cin >> u >> x;
        val[u] = x;
        dfs(0, u, 0);
        //cout << ans << ' ';
        res += ans * i * i;
        res %= mod;
    }
    cout << res << '\n';
}

signed main(){
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}