#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;
inline int read(){
    int t=1,num=0;char c=getchar();
    while(c>‘9‘||c<‘0‘){if(c==‘-‘)t=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){num=num*10+c-‘0‘;c=getchar();}
    return num*t;
}
const int maxn=500010;
vector<int>g[maxn];
int d[maxn],n,m,ro,f[maxn][21];
void bfs(int s){
    memset(d,127/3,sizeof(d));
    queue<int>q;q.push(s);d[s]=0;
    while(!q.empty()){
        int x=q.front();q.pop();
        for(int i=0;i<g[x].size();i++){
            int y=g[x][i];
            if(d[y]>d[x]+1){
                d[y]=d[x]+1;q.push(y);
            }
        }
    }
}
void bz(){
    for(int j=1;j<=20;j++)
        for(int i=1;i<=n;i++)
            f[i][j]=f[f[i][j-1]][j-1];
}
int lca(int x,int y){
    if(d[x]<d[y])swap(x,y);
    int tmp=d[x]-d[y];
    for(int i=0;i<=20;i++)
        if((1<<i)&tmp)x=f[x][i];
    if(x==y)return x;
    for(int i=20;i>=0;i--)
        if(f[x][i]!=f[y][i])
            x=f[x][i],y=f[y][i];
    return f[x][0];
}
int main()
{
    n=read();m=read();
    for(int i=1;i<n;i++){
        int a=read(),b=read();
        g[a].push_back(b);f[b][0]=a;
        if(!f[a][0])ro=a;
    }
    bfs(ro);bz();
    for(int i=1;i<=m;i++){
        int a=read(),b=read();
        printf("%d\n",lca(a,b));
    }
    return 0;
}