//
//  na 2376.cpp
//  Competitive Programming
//
//  Created by m2 on 2024/11/20.
//

#include <stdio.h>
#include <iostream>
using namespace std;
typedef long long int ll;
const int maxn = 1e6 + 5, mod = 1e9 + 7;
int n, q, v[maxn], v1[maxn], v2[maxn], p[maxn], ans;
inline int mult(int a, int b){
    return ll(a) * b % mod;
}
inline void add(int &a, int b){
    if((a += b) >= mod)
        a -= mod;
}
inline void qread(int &var){
    var = 0;
    char reg = getchar();
    while(reg - 48 > 9u)
        reg = getchar();
    do{
        var = (var << 1) + (var << 3) + (reg ^ 48);
        reg = getchar();
    }while(reg - 48 < 10u);
}
struct Edge{
    int val;
    Edge* nxt;
    Edge(int val, Edge* nxt): val(val), nxt(nxt) {}
};
Edge *head[maxn];
inline void edge(int st, int en){
    if(head[st])
        head[st] = new Edge(en, head[st]);
    else
        head[st] = new Edge(en, nullptr);
}
void dfs(int idx, int from){
    p[idx] = from;
    for(Edge *e = head[idx]; e; e = e->nxt)
        if(e->val != from)
            dfs(e->val, idx);
}
inline void add(int idx){
    if(p[idx]){
        v1[p[idx]] ^= v[idx];
        if(p[p[idx]])
            v2[p[p[idx]]] ^= v[idx];
    }
}
inline int query(int idx){
    int res = v2[idx] ^ v1[idx] ^ v[idx];
    if(p[idx]){
        res ^= v1[p[idx]] ^ v[idx] ^ v[p[idx]];
        if(p[p[idx]])
            res ^= v[p[p[idx]]];
    }
    return res;
}
//#define READFILE
int main(){
    cin.tie(0)->sync_with_stdio(false);
#if defined(READFILE) && defined(MAC_OS_VERSION_11_0)
    freopen("/Users/m2/Downloads/ex_xor2.in", "r", stdin);
#endif
    qread(n); qread(q);
    for(int i = 1; i <= n; ++i)
        qread(v[i]);
    for(int u, v, i = 1; i < n; ++i){
        qread(u); qread(v);
        edge(u, v);
        edge(v, u);
    }
    dfs(1, 0);
    for(int i = 1; i <= n; ++i)
        add(i);
    for(int x, rv, rans, i = 1; i <= q; ++i){
        qread(x); qread(rv);
        add(x);
        v[x] = rv;
        add(x);
        rans = query(x);
//        cerr << "rans = " << rans << endl;
        add(ans, mult(mult(i, i), rans % mod));
    }
    cout << ans << endl;
    return 0;
}