/*  Erica N  */
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define int long long
#define ull unsigned long long
#define pii pair<int, int>
#define ps second
#define pf first
#define itn int
#define rd read()
int read(){
    int xx = 0, ff = 1;char ch = getchar();
    while (ch < '0' || ch > '9') {if (ch == '-')ff = -1; ch = getchar();}
    while (ch >= '0' && ch <= '9')xx = xx * 10 + (ch - '0'), ch = getchar();
    return xx * ff;
}
// void write(int out) {
// 	if (out < 0)
// 		putchar('-'), out = -out;
// 	if (out > 9)
// 		write(out / 10);
// 	putchar(out % 10 + '0');
// }
#define cdbg(x...) do { cerr << #x << " -> "; err(x); } while (0)
void err() { cerr << endl; }
template<template<typename...> class T, typename t, typename... A>
void err(T<t> a, A... x) { for (auto v: a) cerr << v << ' '; err(x...); }
template<typename T, typename... A>
void err(T a, A... x) { cerr << a << ' '; err(x...); }


const int N = 2e6 + 5;
const int INF = 1e18;
const int M = 1e7;
const int MOD = 1e9 + 7;


int fa[N],g[N];
int a[N];
int f[N];//节点x的儿子的异或和

vector<int> e[N];
void add(int a,int b){
    e[a].pb(b);
    e[b].pb(a);
}


void dfs(int x,int ft){
    fa[x]=ft;
    f[x]=a[x];
    for(auto v:e[x]){
        if(v==ft)continue;
        f[x]^=a[v];
        dfs(v,x);
    }
}

void dfs2(int x,int ft){

    g[x]^=f[fa[x]];
    g[x]^=a[fa[fa[x]]];
    for(auto v:e[x]){
        if(v==ft)continue;
        g[x]^=f[v];
        dfs2(v,x);
    }
} 

int tag[N],tag2[N];

signed main() {
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);

    int n=rd,q=rd;
    for(int i=1;i<=n;i++){
        a[i]=rd;
    }

    for(int i=1;i<n;i++){
        add(rd,rd);
    }
    add(n+1,1);
    add(n+2,n+1);
    // f[0]=a[1];
    dfs(n+2,0);
    dfs2(n+2,0);
    int ans=0;

    // for(int i=1;i<=n;i++)cdbg(f[i]);
    // for(int i=1;i<=n;i++)cdbg(g[i]);

    for(int i=1;i<=q;i++){
        int x=rd,v=rd;
        // w[x]=v;
        tag2[x]^=a[x]^v;
        tag[fa[x]]^=a[x]^v;
        g[fa[fa[x]]]^=a[x]^v;
        g[fa[x]]^=a[x]^v;

        int res=g[x]^tag[fa[x]]^tag2[fa[x]]^tag2[fa[fa[x]]];
        a[x]=v;
        ans=(ans+res*i%MOD*i%MOD)%MOD;
        
    }
    cout<<ans<<endl;


    

}