#include <cstdio>
#include <vector>
#define N 205000
using namespace std;
vector<int>Graph[N];
int max(int a,int b) {return a>b?a:b;}
int min(int a,int b) {return a>b?b:a;}
int Pri[N],n,m,dep[N],dad[N][25],Max[N][25],Min[N][25],up[N][25],down[N][25];
void dfs(int x)
{dep[x]=dep[dad[x][0]]+1;for(int i=0;dad[x][i];++i){Max[x][i+1]=max(Max[x][i],Max[dad[x][i]][i]);Min[x][i+1]=min(Min[x][i],Min[dad[x][i]][i]);up[x][i+1]=max(up[x][i],Max[dad[x][i]][i]-Min[x][i]);up[x][i+1]=max(up[x][i],up[dad[x][i]][i]);down[x][i+1]=max(down[x][i],down[dad[x][i]][i]);down[x][i+1]=max(down[x][i],Max[x][i]-Min[dad[x][i]][i]);dad[x][i+1]=dad[dad[x][i]][i];}for(int i=0;i<Graph[x].size();++i){int v=Graph[x][i];if(dad[x][0]!=v){dad[v][0]=x;Max[v][0]=max(Pri[x],Pri[v]);Min[v][0]=min(Pri[x],Pri[v]);up[v][0]=max(0,Pri[x]-Pri[v]);down[v][0]=min(0,Pri[v]-Pri[x]);dfs(v);}}
}
int lca(int x,int y)
{if(dep[x]>dep[y]) swap(x,y);for(int i=20;i>=0;--i)if(dep[dad[y][i]]>=dep[x]) y=dad[y][i];if(x==y) return x;for(int i=20;i>=0;--i)if(dad[y][i]!=dad[x][i]) x=dad[x][i],y=dad[y][i];return dad[x][0];
}
int Up(int x,int y)
{int ret=0,Minn=0x7fffffff;if(dep[x]>dep[y]) swap(x,y);for(int i=20;i>=0;--i){if(dep[dad[y][i]]>=dep[x]){ret=max(ret,up[y][i]);ret=max(ret,Max[y][i]-Minn);Minn=min(Minn,Min[y][i]);y=dad[y][i];}}if(x==y) return ret;for(int i=20;i>=0;--i){if(dad[y][i]!=dad[x][i]){ret=max(ret,max(up[y][i],up[x][i]));ret=max(ret,max(Max[y][i]-Minn,Max[x][i]-Minn));Minn=min(Minn,min(Min[y][i],Min[x][i]));y=dad[y][i];x=dad[x][i];}}return ret;
}
int Down(int x,int y)
{int ret=0,Maxn=0;if(dep[x]>dep[y]) swap(x,y);for(int i=20;i>=0;--i){if(dep[dad[y][i]]>=dep[x]){ret=min(ret,down[y][i]);ret=min(ret,Maxn-Min[y][i]);Maxn=max(Maxn,Max[y][i]);y=dad[y][i];}}if(x==y) return ret;for(int i=20;i>=0;--i){if(dad[y][i]!=dad[x][i]){ret=min(ret,min(down[y][i],down[x][i]));ret=min(ret,min(Maxn-Min[y][i],Maxn-Min[x][i]));Maxn=max(Maxn,max(Max[y][i],Max[x][i]));y=dad[y][i];x=dad[x][i];}}return ret;
}
int query_max(int x,int y)
{if(dep[x]>dep[y]) swap(x,y);int ret=Pri[y];for(int i=20;i>=0;--i){if(dep[dad[y][i]]>=dep[x]){ret=max(ret,Max[y][i]);y=dad[y][i];}}if(x==y) return ret;for(int i=20;i>=0;--i){if(dad[y][i]!=dad[x][i]){ret=max(ret,Max[x][i]);ret=max(ret,Max[y][i]);x=dad[x][i];y=dad[y][i];}}return ret;
}
int query_min(int x,int y)
{if(dep[x]>dep[y]) swap(x,y);int ret=Pri[y];for(int i=20;i>=0;--i){if(dep[dad[y][i]]>=dep[x]){ret=min(ret,Min[y][i]);y=dad[y][i];}}if(x==y) return ret;for(int i=20;i>=0;--i){if(dad[y][i]!=dad[x][i]){ret=min(ret,Min[x][i]);ret=min(ret,Min[y][i]);x=dad[x][i];y=dad[y][i];}}return ret;
}
int main()
{scanf("%d",&n);for(int i=1;i<=n;++i) scanf("%d",&Pri[i]);for(int x,y,i=1;i<n;++i){scanf("%d%d",&x,&y);Graph[x].push_back(y);Graph[y].push_back(x);  }dfs(1);scanf("%d",&m);for(int x,y;m--;){scanf("%d%d",&x,&y);if(x==y) {puts("0");continue;} int z=lca(x,y),ans=0;ans=max(ans,Up(x,z));ans=max(ans,Down(y,z));ans=max(ans,query_max(x,z)-query_min(y,z));printf("%d\n",ans);}return 0;
}