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         #define maxn 500000using namespace std;int dp[1001000][20];int to[maxn*2],be[maxn*2],ne[2*maxn],e;int deep[maxn*2],first[2*maxn],cnt,n;bool p[maxn];void add(int x,int y){	to[++e]=y;	ne[e]=be[x];	be[x]=e;}void dfs(int v,int deepth){	p[v]=1,dp[++cnt][0]=v,first[v]=cnt;	for(int i=be[v];i;i=ne[i]){		if(!p[to[i]]){			deep[to[i]]=deepth;			dfs(to[i],deepth+1);			dp[++cnt][0]=v;		}	}}void st(int n){	int len=log2(n)+1;	for(int i=1;i<=len;i++){		for(int j=1;j<=n;j++){			if(j+(1<<(i-1))>n)continue;			if(deep[dp[j][i-1]]
         
          <<(i-1))][i-1]]) dp[j][i]=dp[j][i-1]; else dp[j][i]=dp[j+(1<<(i-1))][i-1]; } }}int rmq(int a,int b){ if(a>b)swap(a,b); int k1=log2(b-a+1); int x,y; x=dp[a][k1]; y=dp[b-(1<
          
           deep[y])return y; else return x;}int main(){ int i,j,k,m; scanf("%d%d%d",&n,&m,&k); for(i=1;i<=n-1;i++){ int x,y; scanf("%d%d",&x,&y); add(x,y); add(y,x); } dfs(k,1); st(cnt); for(i=1;i<=m;i++){ int x,y; scanf("%d%d",&x,&y); printf("%d\n",rmq(first[x],first[y])); } return 0;}