解析：

其實就是這道題放到了$LCT$上來做，其實操作基本都是一樣的。

拿來做$LCT$的練手題還不錯。

程式碼：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define re register
#define gc getchar
#define pc putchar
#define cs const

inline
ll getint(){
	re ll num;
	re char c;
	while(!isdigit(c=gc()));num=c^48;
	while(
 
isdigit(c=gc()))num=(num<<1)+(num<<3)+(c^48);
	return num;
}

inline
void outint(int a){
	static char ch[23];
	if(a==0)pc('0');
	while(a)ch[++ch[0]]=a-a/10*10,a/=10;
	while(ch[0])pc(ch[ch[0]--]^48);
}

inline
char getop(){
	re char c;
	while('+'!=(c=gc())&&'-'!=c&&'*'!=c&&'/'
 
!=c);
	return c;
}

cs ll mod=51061;
typedef struct splay_node *point;
struct splay_node{
	point son[2],fa;
	bool tag;
	int mul,add,sum,val,siz;
	splay_node(){
		siz=1;
		son[0]=son[1]=fa=NULL;
		tag=add=0;
		mul=sum=val=1;
	}
	
	point &lc(){return son[0];}
	point &rc(){return son[1];}
	
	bool isroot
 
(){return !fa||(fa->son[0]!=this&&fa->son[1]!=this);}
	bool which(){return fa->son[1]==this;}
	
	void pushnow(int Mul,int Add){
		sum=(1ll*sum*Mul%mod+siz*Add%mod)%mod;
		val=(1ll*val*Mul%mod+Add)%mod;
		add=(1ll*add*Mul%mod+Add)%mod;
		mul=1ll*mul*Mul%mod;
	}
	
	void pushdown(){
		if(tag){
			swap(son[0],son[1]);
			if(son[0])son[0]->tag^=1;
			if(son[1])son[1]->tag^=1;
			tag=0;
		}
		if(mul!=1||add){
			if(son[0])son[0]->pushnow(mul,add);
			if(son[1])son[1]->pushnow(mul,add);
			mul=1,add=0;
		}
	}
	
	void pushup(){
		siz=(son[0]?son[0]->siz:0)+(son[1]?son[1]->siz:0)+1;
		sum=((son[0]?son[0]->sum:0)+(son[1]?son[1]->sum:0)+val)%mod;
	}
};

cs int N=100005;
struct Link_Cut_Tree{
	splay_node ttt[N];
	
	void Rotate(point now){
		point Fa=now->fa,FA=Fa->fa;
		bool pos=now->which();
		if(FA&&!Fa->isroot())FA->son[Fa->which()]=now;
		Fa->fa=now;
		now->fa=FA;
		Fa->son[pos]=now->son[!pos];
		if(Fa->son[pos])Fa->son[pos]->fa=Fa;
		now->son[!pos]=Fa;
		Fa->pushup();
		now->pushup();
	}
	
	void Splay(point now){
		static point q[N];
		static int qn;
		q[qn=1]=now;
		for(point Fa=now;!Fa->isroot();Fa=Fa->fa)q[++qn]=Fa->fa;
		for(int re i=qn;i;--i)q[i]->pushdown();
		for(point Fa;!now->isroot();Rotate(now))
		if(!(Fa=now->fa)->isroot())Rotate(Fa->which()==now->which()?Fa:now);
	}
	
	void access(point now){
		for(point son=NULL;now;son=now,now=now->fa)
		Splay(now),now->rc()=son,now->pushup();
	}
	
	void makeroot(point now){
		access(now),Splay(now);
		now->tag^=1;
	}
	
	void link(point u,point v){
		makeroot(u),u->fa=v;
	}
	void link(int u,int v){link(&ttt[u],&ttt[v]);}
	
	void cut(point u,point v){
		makeroot(u),access(v),Splay(v);
		v->lc()=u->fa=NULL;
	}
	void cut(int u,int v){cut(&ttt[u],&ttt[v]);}
	
	void add(point u,point v,int val){
		makeroot(u),access(v),Splay(v);
		v->pushnow(1,val);
	}
	void add(int u,int v,int val){add(&ttt[u],&ttt[v],val);}
	
	void mul(point u,point v,int val){
		makeroot(u),access(v),Splay(v);
		v->pushnow(val,0);
	}
	void mul(int u,int v,int val){mul(&ttt[u],&ttt[v],val);}
	
	int query(point u,point v){
		makeroot(u);
		access(v);
		Splay(v);
		return v->sum;
	}
	int query(int u,int v){return query(&ttt[u],&ttt[v]);}
	
}LCT;

int n,q;
signed main(){
	n=getint(),q=getint();
	for(int re i=1;i<n;++i){
		int u=getint(),v=getint();
		LCT.link(u,v);
	}
	while(q--){
		char op=getop();
		int u=getint(),v=getint();
		switch(op){
			case '+':{
				int val=getint();
				LCT.add(u,v,val);
				break;
			}
			case '-':{
				LCT.cut(u,v);
				u=getint(),v=getint();
				LCT.link(u,v);
				break;
			}
			case '*':{
				int val=getint();
				LCT.mul(u,v,val);
				break;
			}
			case '/':{
				outint(LCT.query(u,v)),pc('\n');
				break;
			}
		}
	}
	return 0;
}