#include <cstdio>
#include <vector>
using namespace std;
const int mod = 1e9 + 7;
int n, q, u, v, x, y;
vector<int> G[1000010];
int fa[1000010], a[1000010];
int x1[1000010], x2[1000010];
long long ans;
void dfs(int u, int f = 0) {
    fa[u] = f;
    x1[u] = a[u];
    x2[u] = a[u];
    for (int v : G[u]) {
        if (v == f) continue;
        dfs(v, u);
        x1[u] ^= a[v];
        x2[u] ^= x1[v];
    }
}
int main() {
    scanf("%d%d", &n, &q);
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
    }
    for (int i = 1; i < n; i++) {
        scanf("%d%d", &u, &v);
        G[u].push_back(v);
        G[v].push_back(u);
    }
    dfs(1);
    for (int i = 1; i <= q; i++) {
        scanf("%d%d", &x, &y);
        x1[x] ^= a[x];
        x2[x] ^= a[x];
        if (fa[x]) {
            x1[fa[x]] ^= a[x];
            x2[fa[x]] ^= a[x];
        }
        if (fa[fa[x]]) {
            x2[fa[fa[x]]] ^= a[x];
        }
        a[x] = y;
        x1[x] ^= a[x];
        x2[x] ^= a[x];
        if (fa[x]) {
            x1[fa[x]] ^= a[x];
            x2[fa[x]] ^= a[x];
        }
        if (fa[fa[x]]) {
            x2[fa[fa[x]]] ^= a[x];
        }
        int nowans = 0;
        nowans = x1[fa[x]] ^ a[fa[fa[x]]] ^ x2[x] ^ a[x];
        ans += 1ll * nowans * i % mod * i % mod;
        ans %= mod;
    }
    printf("%lld\n", ans);
    return 0;
}