#include<cstdio>

 #include<iostream>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 using namespace std;

 int n,m;

 struct nod{

     int y;

     int next;

 }e[];

 int head[]={};

 int dep[]={};

 int size[]={};

 int son[]={};

 int top[]={};

 int f[]={};

 int tot=;

 void init(int x,int y){

     e[++tot].next=head[x];

     head[x]=tot;

     e[tot].y=y;

 }

 void dfs1(int x){

     dep[x]=dep[f[x]]+;

     size[x]=;

     for(int i=head[x];i;i=e[i].next){

         if(e[i].y!=f[x]&&!f[e[i].y]){

             f[e[i].y]=x;

             dfs1(e[i].y);

             size[x]+=size[e[i].y];

             if(size[son[x]]<size[e[i].y]) son[x]=e[i].y;

         }

     }

 }

 void dfs2(int x){

     if(x==son[f[x]])top[x]=top[f[x]];

     else top[x]=x;

     for(int i=head[x];i;i=e[i].next){

         if(f[e[i].y]==x) dfs2(e[i].y);

     }

 }

 int ask(int x,int y){

     while(top[x]!=top[y]){

         if(dep[top[x]]>dep[top[y]]) x=f[top[x]];

         else y=f[top[y]];

     }

     if(dep[x]<dep[y]) return x;

     else return y;

 }

 int main(){

     scanf("%d%d",&n,&m);

     int x,y;

     for(int i=;i<n;i++){

         scanf("%d%d",&x,&y);

         init(x,y);

         init(y,x);

     }

     dfs1();

     dfs2();

     for(int i=;i<=m;i++){

         scanf("%d%d",&x,&y);

         printf("%d\n",ask(x,y));

     }

     return ;

 }