#include<bits/stdc++.h>
using namespace std;
int n, m, val[1000006], head[1000006], nxt[2000006], to[2000006], ccnt, fa[1000006], ffa[1000006], sum[1000006], ssum[1000006];
long long ans[1000006], cnt;
const long long mod = 1000000007;
inline void add(int p, int q) {
	nxt[++ccnt] = head[p];
	to[ccnt] = q;
	head[p] = ccnt;
}
inline void dfs(int p) {
	sum[fa[p]] ^= val[p];
	sum[ffa[p]] ^= val[p];
	ssum[fa[p]] ^= val[p];
	for (int i = head[p]; i; i = nxt[i]) {
		if (to[i] != fa[p]) {
			fa[to[i]] = p;
			ffa[to[i]] = fa[p];
			dfs(to[i]);
		}
	}
}
signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> val[i];
	}
	int p, q;
	for (int i = 1; i < n; i++) {
		cin >> p >> q;
		add(p, q);
		add(q, p);
	}
	dfs(1);
	for (int i = 1; i <= m; i++) {
		cin >> p >> q;
		ssum[fa[p]] ^= val[p];
		sum[fa[p]] ^= val[p];
		sum[ffa[p]] ^= val[p];
		val[p] = q;
		ssum[fa[p]] ^= val[p];
		sum[fa[p]] ^= val[p];
		sum[ffa[p]] ^= val[p];
		ans[i] = (sum[p] ^ ssum[fa[p]] ^ val[fa[p]] ^ val[ffa[p]]);
		cnt += ((ans[i] * i) % mod * i) % mod;
		cnt %= mod;
	}
	cout << cnt;
}