//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
#define V vector
#define all0(x) (x).begin(),(x).end()
#define all1(x) (x).begin()+1,(x).end()
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#ifdef LOCAL
#define cin std::cin
#define cout std::cout
#endif
typedef long long LL;
typedef pair<int, int> pi;
typedef pair<LL, LL> pl;

const int MN = 5e5 + 20;//MaxN 记得改一下
const int INF = 2e9+1000;//INF
const LL INFLL = 8e18+1000;//INF long long 
//模板区域~~~~~~~

//模板结束~~~~~~~
V<int> e[MN];
int gro[MN][25]; 
int dep[MN];
void dfs1(int x,int p){
    gro[x][0]=p;
    for(auto y: e[x]){
        if(y==p) continue;
        dep[y]=dep[x]+1;
        dfs1(y,x);
    }
}
void solve() {
    int n,q,root;cin>>n>>q>>root;
    for(int i=1;i<n;i++){
        int a,b;cin>>a>>b;
        e[a].pb(b);
        e[b].pb(a);
    }
    dfs1(root,0);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=24;j++){
            gro[i][j]=gro[gro[i][j-1]][j-1];
        }
    }
    for(int i=1;i<=q;i++){
        int a,b;cin>>a>>b;
        if(a==b) {
            cout<<b<<"\n";
            return;
        }
        if(dep[a]<dep[b]) swap(a,b);
        int dis=dep[a]-dep[b];
        for(int i=0;i<=30;i++) {
            if((1<<i)&dis) a=gro[a][i];
        }
        if(a==b) {
            cout<<b<<"\n";
            continue;
        }
        for(int i=24 ;i>=0;i--){
            if(gro[a][i]!=gro[b][i]) a=gro[a][i],b=gro[b][i];
        }
        cout<<gro[a][0]<<"\n";  
    }
}
int main() {
#ifndef LOCAL
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#endif
#ifdef LOCAL
   freopen("in.in","r",stdin);
   freopen("out.out","w",stdout);
#endif
    int tt=1;
    //cin >> tt;
    while (tt--) 
    solve();
}