/*我尼玛 又一个min打成max 看了半天....*/#include<iostream>#include<cstdio>#include<cstring>#define maxn 200010#define inf 0x7fffffffusing namespace std;int n,m,head[maxn],num,v[maxn],fa[maxn][25],c[maxn];int mii[maxn][25],mxx[maxn][25],up[maxn][25],down[maxn][25];struct node{    int v,pre;}e[maxn*2];int init(){    int x=0;char s=getchar();    while(s<‘0‘||s>‘9‘)s=getchar();    while(s>=‘0‘&&s<=‘9‘){x=x*10+s-‘0‘;s=getchar();}    return x;}void Add(int from,int to){    num++;e[num].v=to;    e[num].pre=head[from];    head[from]=num;}void Dfs(int now,int from,int dep,int val){    fa[now][0]=from;c[now]=dep;    mii[now][0]=min(val,v[now]);    mxx[now][0]=max(val,v[now]);    up[now][0]=max(0,v[from]-v[now]);    down[now][0]=max(0,v[now]-v[from]);    for(int i=head[now];i;i=e[i].pre){        if(e[i].v==from)continue;        Dfs(e[i].v,now,dep+1,v[now]);    }}void Get_fa(){    for(int j=1;j<=20;j++)        for(int i=1;i<=n;i++){            fa[i][j]=fa[fa[i][j-1]][j-1];            mii[i][j]=min(mii[i][j-1],mii[fa[i][j-1]][j-1]);            mxx[i][j]=max(mxx[i][j-1],mxx[fa[i][j-1]][j-1]);            up[i][j]=max(up[i][j-1],up[fa[i][j-1]][j-1]);            up[i][j]=max(up[i][j],mxx[fa[i][j-1]][j-1]-mii[i][j-1]);            down[i][j]=max(down[i][j-1],down[fa[i][j-1]][j-1]);            down[i][j]=max(down[i][j],mxx[i][j-1]-mii[fa[i][j-1]][j-1]);        }}int LCA(int a,int b){    if(c[a]<c[b])swap(a,b);    int t=c[a]-c[b];    for(int i=0;i<=20;i++)        if((1<<i)&t)a=fa[a][i];    if(a==b)return a;    for(int i=20;i>=0;i--)        if(fa[a][i]!=fa[b][i]){            a=fa[a][i];            b=fa[b][i];        }    return fa[a][0];}int Up_lca(int a,int b){    int t=c[a]-c[b],ret=0,minner=inf;    for(int i=0;i<=20;i++)        if((1<<i)&t){            ret=max(ret,up[a][i]);            ret=max(ret,mxx[a][i]-minner);            minner=min(minner,mii[a][i]);            a=fa[a][i];        }    return ret;}int Down_lca(int a,int b){    int t=c[a]-c[b],ret=0,maxxer=0;    for(int i=0;i<=20;i++)        if((1<<i)&t){            ret=max(ret,down[a][i]);            ret=max(ret,maxxer-mii[a][i]);            maxxer=max(maxxer,mxx[a][i]);            a=fa[a][i];        }    return ret;}int Query_max(int a,int b){    int t=c[a]-c[b],maxxer=v[a];    for(int i=0;i<=20;i++)        if((1<<i)&t){            maxxer=max(maxxer,mxx[a][i]);            a=fa[a][i];        }    return maxxer;}int Query_min(int a,int b){    int t=c[a]-c[b],minner=v[a];    for(int i=0;i<=20;i++)        if((1<<i)&t){            minner=min(minner,mii[a][i]);            a=fa[a][i];        }    return minner;}int main(){    n=init();    for(int i=1;i<=n;i++)        v[i]=init();    int u,v;    for(int i=1;i<n;i++){        u=init();v=init();        Add(u,v);Add(v,u);    }    memset(mii,127,sizeof(mii));    Dfs(1,0,0,0);Get_fa();    m=init();    while(m--){        u=init();v=init();        int anc=LCA(u,v);        //printf("%d\n",anc);        int ans=0;        ans=max(Up_lca(u,anc),Down_lca(v,anc));        ans=max(ans,Query_max(v,anc)-Query_min(u,anc));        printf("%d\n",ans);    }    return 0;}