1 #include<iostream>
2 #include<cstdio>
3 #include<cstring>
4 #include<cstdio>
5 #include<algorithm>
6 using namespace std;
7 #define maxn 1000010
8 #define IL inline
9 IL void read(int &x)
10 {
11 x=0;int f=1;char ch=getchar();
12 while(ch<'0'||ch>'9'){if(ch=='-')f=-f;ch=getchar();}
13 while(ch>='0'&&ch<='9'){x=x*10+ch-'0',ch=getchar();}x*=f;
14 }
15
16 int n,m,s,tot;
17 int first[maxn],deep[maxn],fa[maxn],son[maxn],size[maxn],top[maxn];
18 struct edge{
19 int nextx,to;
20 }e[maxn];
21
22 void add(int u,int v)
23 {
24 tot++;
25 e[tot].nextx=first[u];
26 first[u]=tot;
27 e[tot].to=v;
28 }
29
30 void dfs1(int x,int f,int depth)
31 {
32 fa[x]=f;
33 deep[x]=depth;
34 size[x]=1;
35 int mson=-1;
36 for(int i=first[x];i;i=e[i].nextx)
37 {
38 int u=e[i].to;
39 if(u==f)continue;
40 dfs1(u,x,depth+1);
41 size[x]+=size[u];
42 if(size[u]>mson)
43 mson=size[u],son[x]=u;
44 }
45 }
46
47 void dfs2(int x,int topf)
48 {
49 top[x]=topf;
50 if(!son[x])return;
51 dfs2(son[x],topf);
52 for(int i=first[x];i;i=e[i].nextx)
53 {
54 int u=e[i].to;
55 if(u==fa[x]||u==son[x])continue;
56 dfs2(u,u);
57 }
58 }
59
60 int main()
61 {
62 read(n),read(m),read(s);
63 for(int i=1;i<=n-1;i++)
64 {
65 int a,b;
66 read(a),read(b);
67 add(a,b),add(b,a);
68 }
69 dfs1(s,s,1);
70 dfs2(s,s);
71 for(int i=1;i<=m;i++)
72 {
73 int x,y;
74 read(x),read(y);
75 while(top[x]!=top[y])
76 {
77 if(deep[top[x]]>=deep[top[y]])x=fa[top[x]];
78 else y=fa[top[y]];
79 }
80 if(deep[x]<=deep[y])cout<<x<<"\n";
81 else cout<<y<<"\n";
82 }
83 return 0;
84 }
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