#include<bits/stdc++.h>
#define int long long
using namespace std;
namespace IO{
	template<typename T> inline void read(T &x){
		bool f=1;x=0;char ch=getchar();
		while(ch<'0'||ch>'9'){if(ch=='-')f=0;ch=getchar();}
		while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+(ch&15),ch=getchar();
		x=f?x:-x;
	}
	template<typename T> inline void write(T x){
		if(x<0) putchar('-'),x=-x;
	   	if(x>9) write(x/10);
	   	putchar(('0'+x%10));
	}
	template <typename T,typename ...Args> inline void read(T &x,Args &...args){read(x);read(args...);}
	template<typename T> inline void write(T x,char c){write(x),putchar(c);}
}
using namespace IO;
const int mod=1e9+7;
int n,q;
vector <int> e[1000005];
int a[1000005],val[1000005],sum[1000005],fa[1000005];
void dfs(int u, int fath) {
	for(auto v:e[u]){
		if(v==fath)continue;
		fa[v]=u;dfs(v,u);
		val[u]^=a[v];
		sum[u]^=val[v];
	}
}
signed main(){
	read(n,q);
	for(int i=1;i<=n;i++)read(a[i]);
	for(int i=1,x,y;i<n;i++){
		read(x,y);
		e[x].push_back(y);
		e[y].push_back(x);
	}
	int root=1,res=0;
	dfs(root,0);
	for(int i=1,x,v;i<=q;i++){
		read(x,v);
		val[fa[x]]^=a[x]^v;
		sum[fa[fa[x]]]^=a[x]^v;
		a[x]=v;
		int ans=val[x]^sum[x]^a[fa[x]]^a[fa[fa[x]]]^val[fa[x]];
		res=(res+ans*i%mod*i%mod)%mod;
	}
	write(res);
	return 0;
}