嘟嘟嘟



写完lct的板儿后觉得这就是一道大水题。

连pushup都不用。

不过还是因为一个zz的错误debug了一小会儿（Link的时候连出自环……）

还有一件事就是Cut的时候判断条件还得加上，因为我这种写法会改变树的形态，不加后面就删错边了。

#include<cstdio>

#include<iostream>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<cstdlib>

#include<cctype>

#include<vector>

#include<stack>

#include<queue>

using namespace std;

#define enter puts("")

#define space putchar(' ')

#define Mem(a, x) memset(a, x, sizeof(a))

#define rg register

#define In inline

typedef long long ll;

typedef double db;

const int INF = 0x3f3f3f3f;

const db eps = 1e-8;

const int maxn = 1e4 + 5;

inline ll read()

{

  ll ans = 0;

  char ch = getchar(), last = ' ';

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

  while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();

  if(last == '-') ans = -ans;

  return ans;

}

inline void write(ll x)

{

  if(x < 0) x = -x, putchar('-');

  if(x >= 10) write(x / 10);

  putchar(x % 10 + '0');

}

int n, m;

char c[10];

struct Tree

{

  int ch[2], fa, rev;

}t[maxn];

In void change(int now)

{

  swap(t[now].ch[0], t[now].ch[1]); t[now].rev ^= 1;

}

In void pushdown(int now)

{

  if(t[now].rev)

    {

      if(t[now].ch[0]) change(t[now].ch[0]);

      if(t[now].ch[1]) change(t[now].ch[1]);

      t[now].rev = 0;

    }

}

In bool n_root(int x)

{

  return t[t[x].fa].ch[0] == x || t[t[x].fa].ch[1] == x;

}

void rotate(int x)

{

  int y = t[x].fa, z = t[y].fa, k = (t[y].ch[1] == x);

  if(n_root(y)) t[z].ch[t[z].ch[1] == y] = x; t[x].fa = z;

  t[y].ch[k] = t[x].ch[k ^ 1]; t[t[x].ch[k ^ 1]].fa = y;

  t[x].ch[k ^ 1] = y; t[y].fa = x;

}

int st[maxn], top = 0;

In void splay(int x)

{

  int y = x;

  st[top = 1] = y;

  while(n_root(y)) y = t[y].fa, st[++top] = y;

  while(top) pushdown(st[top--]);

  while(n_root(x))

    {

      int y = t[x].fa, z = t[y].fa;

      if(n_root(y)) rotate(((t[z].ch[0] == y) ^ (t[y].ch[0] == x)) ? x : y);

      rotate(x);

    }

}

In void access(int x)

{

  int y = 0;

  while(x)

    {

      splay(x); t[x].ch[1] = y;

      y = x; x = t[x].fa;

    }

}

In int find_root(int x)

{

  access(x); splay(x);

  while(t[x].ch[0]) pushdown(x), x = t[x].ch[0];

  return x;

}

In void make_root(int x)

{

  access(x); splay(x);

  change(x);

}

In void Link(int x, int y)

{

  make_root(x);

  if(find_root(y) != x) t[x].fa = y;

}

In void Cut(int x, int y)

{

  make_root(x);

  if(find_root(y) == x && t[x].fa == y && !t[x].ch[1])

  	t[x].fa = t[y].ch[0] = 0;

}

In bool query(int x, int y)

{

  make_root(x);

  return find_root(y) == x;

}

int main()

{

  n = read(); m = read();

  for(int i = 1; i <= m; ++i)

    {

      scanf("%s", c); int x = read(), y = read();

      if(c[0] == 'C') Link(x, y);

      else if(c[0] == 'D') Cut(x, y);

      else puts(query(x, y) ? "Yes" : "No");

    }

  return 0;

}