AC on #1，其余WA。

code:

#include <bits/stdc++.h>
#define N 30005
using namespace std;
int T, x, y, fa[N], dis[N];
char op;
void init()
{
	for (int i = 0; i < N; i++)
		fa[i] = i, dis[i] = 0;
}
int find(int x)
{
	if (fa[x] == x)
		return x;
	int tmp = fa[x];
	fa[x] = find(fa[x]);
	dis[x] += dis[tmp];
	return fa[x];
}
void merge(int x, int y)
{
	int fx = find(x), fy = find(y);
	if (fx != fy)
	{
		fa[fx] = fy;
		dis[fx] = 1;
	}
}
int main()
{
	init();
	cin >> T;
	while (T--)
	{
		cin >> op >> x >> y;
		if (op == 'M'){
			
			merge(x, y);
//			for (int i = 1; i <= 4; i++)
//				cout << fa[i] << ' ';
//			cout << endl;
		}
		else if (op == 'C')
		{
			int fx = find(x), fy = find(y);
			if (fx != fy)
				cout << -1 << endl;
			else
			{
				if (dis[x] < dis[y])
					swap(x, y);
				cout << dis[x] - dis[y] - 1 << endl;
			}
		}
	}
	return 0;
}