#include <bits/stdc++.h> // 自己写的，因为原题机boom了（
#define int long long 
using namespace std;

const int N = 1e6 + 5, mod = 1e9 + 7;

vector <int> e[N];
int val[N], val1[N], val2[N], fa[N];

void dfs(int u, int fath) {
	for (auto v : e[u]) {
		if (v == fath) continue;
		fa[v] = u;
		dfs(v, u);
		val1[u] ^= val[v];
		val2[u] ^= val1[v];
	}
}

signed main() {
//	freopen("ex_xor2.in", "r", stdin);
//	freopen("ex_xor2.out", "w", stdout);
	cin.tie(0); ios::sync_with_stdio(0);
	int n, q; cin >> n >> q;
	for (int i = 1; i <= n; i++) cin >> val[i];
	for (int i = 1; i < n; i++) {
		int x, y; cin >> x >> y;
		e[x].push_back(y);
		e[y].push_back(x);
	}
	
	int root = 1;
	dfs(root, 0);
	
	int res = 0;
	for (int i = 1; i <= q; i++) {
		int x, v; cin >> x >> v;
		val1[fa[x]] ^= val[x] ^ v;
		val2[fa[fa[x]]] ^= val[x] ^ v;
		
		val[x] = v;
		int ans = val1[x] ^ val2[x] ^ val[fa[x]] ^ val[fa[fa[x]]] ^ 
			val1[fa[x]];
		
		(res += ans * i % mod * i % mod) %= mod;
	}
	
	cout << res;
	return 0;
}