用合并直径的定理，并查集维护每棵树的直径
主要是看看过了这么久自己的lct有没有变残废2333（1A还行
#include<stdio.h>
int ch[300010][2],fa[300010],r[300010],siz[300010],sfa[300010],d1[300010],d2[300010];
void pushup(int x){siz[x]=siz[ch[x][0]]+siz[ch[x][1]]+1;}
void swap(int&a,int&b){a^=b^=a^=b;}
void rev(int x){
r[x]^=1;
swap(ch[x][0],ch[x][1]);
}
void pushdown(int x){
if(r[x]){
if(ch[x][0])rev(ch[x][0]);
if(ch[x][1])rev(ch[x][1]);
r[x]=0;
}
}
bool isrt(int x){return ch[fa[x]][0]!=x&&ch[fa[x]][1]!=x;}
void rot(int x){
int y,z,f,B;
y=fa[x];
z=fa[y];
f=(ch[y][0]==x);
B=ch[x][f];
fa[x]=z;
fa[y]=x;
if(B)fa[B]=y;
ch[x][f]=y;
ch[y][f^1]=B;
if(ch[z][0]==y)ch[z][0]=x;
if(ch[z][1]==y)ch[z][1]=x;
pushup(y);
pushup(x);
}
void gao(int x){
if(fa[x])gao(fa[x]);
pushdown(x);
}
void splay(int x){
gao(x);
int y,z;
while(!isrt(x)){
y=fa[x];
z=fa[y];
if(!isrt(y))rot((ch[z][0]==y&&ch[y][0]==x)||(ch[z][1]==y&&ch[y][1]==x)?y:x);
rot(x);
}
}
void access(int x){
int y=0;
while(x){
splay(x);
ch[x][1]=y;
pushup(x);
y=x;
x=fa[x];
}
}
void makert(int x){
access(x);
splay(x);
rev(x);
}
void link(int x,int y){
makert(x);
fa[x]=y;
}
int query(int x,int y){
makert(x);
access(y);
splay(y);
return siz[y]-1;
}
int getfa(int x){return(x==sfa[x])?x:(sfa[x]=getfa(sfa[x]));}
int max(int a,int b){return a>b?a:b;}
int main(){
int type,n,m,i,j,x,y,mx,p1,p2,las,tmp,t[4];
scanf("%d%d%d",&type,&n,&m);
for(i=1;i<=n;i++){
siz[i]=1;
sfa[i]=d1[i]=d2[i]=i;
}
las=0;
while(m--){
scanf("%d",&i);
if(i==1){
scanf("%d%d",&x,&y);
if(type==1){
x^=las;
y^=las;
}
link(x,y);
x=getfa(x);
y=getfa(y);
t[0]=d1[x];
t[1]=d2[x];
t[2]=d1[y];
t[3]=d2[y];
mx=0;
for(i=0;i<3;i++){
for(j=i+1;j<4;j++){
tmp=query(t[i],t[j]);
if(tmp>mx){
mx=tmp;
p1=t[i];
p2=t[j];
}
}
}
d1[x]=p1;
d2[x]=p2;
sfa[y]=x;
}else{
scanf("%d",&x);
if(type==1)x^=las;
y=getfa(x);
las=max(query(x,d1[y]),query(x,d2[y]));
printf("%d\n",las);
}
}
}