#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
using namespace std;
int m,n;
vector<int> in(1000000,0);
vector<int> pre(1000000,0);
map<int,int> pos;
void lca(int inl,int inr,int preroot,int inroot,int a,int b){
if(inl > inr)
return;
inroot = pos[pre[preroot]];
int ina = pos[a],inb = pos[b];
if(ina<inroot && inb>inroot || inb<inroot && ina>inroot){
printf("LCA of %d and %d is %d.\n",a,b,pre[preroot]);
}
else if(ina < inroot && inb<inroot){
lca(inl,inroot-1,preroot+1,inroot,a,b);
}
else if(ina > inroot && inb>inroot){
lca(inroot+1,inr,preroot+1+(inroot-inl),inroot,a,b);
}
else if(ina == inroot){
printf("%d is an ancestor of %d.\n",a,b);
}
else if(inb == inroot){
printf("%d is an ancestor of %d.\n",b,a);
}
}
int main(){
int a,b;
cin>>m>>n;
for(int i=1;i<=n;i++){
cin>>in[i];
pos[in[i]] = i;
}
for(int i=1;i<=n;i++)
cin>>pre[i];
for(int i=0;i<m;i++){
cin>>a>>b;
if(pos[a]==0 && pos[b]==0){
printf("ERROR: %d and %d are not found.\n",a,b);
}
else if(pos[a]==0 && pos[b]!=0){
printf("ERROR: %d is not found.\n",a);
}
else if(pos[a]!=0 && pos[b]==0){
printf("ERROR: %d is not found.\n",b);
}
else{
lca(1,n,1,a,a,b);
}
}
return 0;
}
