%:pragma GCC optimize ("Ofast")

 #include<cstdio>

 #include<vector>

 #include<cctype>

 inline int getint() {

     int ch;

     while(!isdigit(ch=getchar()));

     int x=ch^'';

     while(isdigit(ch=getchar())) x=(((x<<)+x)<<)+(ch^'');

     return x;

 }

 const int N=,logN=;

 std::vector<int> e[N];

 int anc[N][logN+]={{}},dep[N];

 inline void add_edge(const int u,const int v) {

     e[u].push_back(v);

     e[v].push_back(u);

 }

 void dfs(const int x,const int parent,const int depth) {

     anc[x][]=parent,dep[x]=depth;

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

         anc[x][i]=anc[anc[x][i-]][i-];

     }

     for(unsigned int i=;i<e[x].size();i++) {

         if(e[x][i]==parent) continue;

         dfs(e[x][i],x,depth+);

     }

 }

 inline void swap(int &a,int &b) {

     int t;

     t=a;

     a=b;

     b=t;

 }

 int LCA(int a,int b) {

     if(dep[a]<dep[b]) swap(a,b);

     for(int i=logN;i>=;i--) {

         if(dep[a]-(<<i)>=dep[b]) a=anc[a][i];

     }

     if(a==b) return a;

     for(int i=logN;i>=;i--) {

         if(anc[a][i]&&anc[a][i]!=anc[b][i]) {

             a=anc[a][i];

             b=anc[b][i];

         }

     }

     return anc[a][];

 }

 int main() {

     int n=getint(),m=getint(),s=getint();

     for(int i=;i<n;i++) add_edge(getint(),getint());

     dfs(s,,);

     while(m--) printf("%d\n",LCA(getint(),getint()));

     return ;

 }