#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<vector>
using namespace std;
typedef long long ll;
const int maxn=40010;
vector<ll>v[maxn][16];
int d[maxn],n,Q,fa[maxn][16],last[maxn],pre[maxn],other[maxn],t;
void add(int x,int y){++t;pre[t]=last[x];last[x]=t;other[t]=y;}
ll x,q[maxn];
vector<ll> uni(vector<ll> a,vector<ll> b){vector<ll>ans;int top=0,lena=a.size(),lenb=b.size();for(int i=0;i<lena;++i)q[++top]=a[i];for(int i=0;i<lenb;++i)q[++top]=b[i];int p=0;for(int j=60;j>=0;--j){bool flag=0;for(int i=p+1;i<=top;++i)if((q[i]>>j)&1){swap(q[i],q[++p]);flag=1;break;}if(!flag)continue;for(int i=1;i<=top;++i)if(i!=p){if((q[i]>>j)&1)q[i]^=q[p];}}for(int i=1;i<=p;++i)ans.push_back(q[i]);return ans;
}
void dfs(int x){for(int i=last[x];i;i=pre[i]){int v=other[i];if(v==fa[x][0])continue;d[v]=d[x]+1;fa[v][0]=x;dfs(v);}
}
int lca(int x,int y){if(d[x]<d[y])swap(x,y);for(int i=15;i>=0;--i)if(d[fa[x][i]]>=d[y])x=fa[x][i];if(x==y)return x;for(int i=15;i>=0;--i)if(fa[x][i]!=fa[y][i])x=fa[x][i],y=fa[y][i];return fa[x][0];
}
int jump(int x,int y){for(int i=15;i>=0;--i){if((1<<i)&y)x=fa[x][i];}return x;
}
vector<ll> qs(int x,int y){int k=log2(d[x]-d[y]+1);return uni(v[x][k],v[jump(x,d[x]-d[y]+1-(1<<k))][k]);
}
int main(){cin>>n>>Q;for(int i=1;i<=n;++i){scanf("%lld",&x);v[i][0].push_back(x);}int a,b,tmp;for(int i=1;i<n;++i){scanf("%d%d",&a,&b);add(a,b);add(b,a);}dfs(1);for(int j=1;j<=15;++j)for(int i=1;i<=n;++i){fa[i][j]=fa[fa[i][j-1]][j-1];v[i][j]=uni(v[i][j-1],v[fa[i][j-1]][j-1]);}while(Q--){scanf("%d%d",&a,&b);tmp=lca(a,b);vector<ll>ans=uni(qs(a,tmp),qs(b,tmp));ll res=0,siz=ans.size();for(int i=0;i<siz;++i)if((res^ans[i])>res)res^=ans[i];printf("%lld\n",res);}return 0;
}