#include<bits/stdc++.h>
#define N 30010
using namespace std;
int f[N],fa[N],sum[N];
int find(int k){
	if(fa[k]==k)return k;
	int p=fa[k];
	fa[k]=find(fa[k]);
	f[k]+=f[p];
}
void un(int x,int y){               //x->y
	x=find(x);y=find(y);
	//fa[x]=y;
	f[x]+=sum[y];
	sum[y]+=sum[x];
}
void pre( ){
	std::ios::sync_with_stdio(0);
	memset(sum,1,sizeof(sum));
	int i;
	for(i=1;i<=30000;i++)fa[i]=i;
}
void work( ){
	char s;
	int x,y;
	cin>>s>>x>>y;
	if(s=='M'){
		un(x,y);
	}else{
		if(find(x)==find(y))
		cout<<abs(f[x]-f[y])<<endl;
		else cout<<"-1"<<endl;
	}
}
int main( ){
	pre( );
	int t;
	cin>>t;
	while(t--)work( );
}

为什么注释掉的一行会导致RE?