#include<bits/stdc++.h>

#define int long long
#define mem(x,y) memset(x,y,sizeof(x))
#define frein freopen("in.in","r",stdin)
#define freout freopen("out.out","w",stdout)
#define debug(x) cout << (#x) << " = " << x << endl;

using namespace std;

int read(){
   int s = 0,w = 1;
   char ch = getchar();
   while(ch < '0' || ch > '9'){if(ch == '-')w = -1;ch = getchar();}
   while(ch >= '0' && ch <= '9')s = s * 10 + ch - '0',ch = getchar();
   return s * w;
}

int n,m;
const int mod = 51061;

struct LCT{
	struct node{
		int fa;
		int son[2];
		int sum;
		int w;
		int siz;
	}e[1000010];
	
	bool lazy[1000010];
	int la1[1000010],la2[1000010];
	
	inline void update(int i){
		e[i].sum = (e[e[i].son[0]].sum + e[e[i].son[1]].sum + e[i].w) % mod;
		e[i].siz = e[e[i].son[0]].siz + e[e[i].son[1]].siz + 1;
	}
	
	inline void pushrev(int i){
		swap(e[i].son[0], e[i].son[1]);
		lazy[i] ^= 1;
	}
	
	inline void pushmul(int i, int d){
		e[i].sum = e[i].sum * d % mod;
		e[i].w = e[i].w * d % mod;
		la1[i] = la1[i] * d % mod;
		la2[i] = la2[i] * d % mod;
	}
	
	inline void pushadd(int i, int d){
		e[i].sum = (e[i].sum + d * e[i].siz) % mod;
		e[i].w = (e[i].w + d) % mod;
		la2[i] = la2[i] * d % mod;
	}
	
	inline void pushdown(int i){
		if(lazy[i]){
			if (e[i].son[0]) pushrev(e[i].son[0]);
			if (e[i].son[1]) pushrev(e[i].son[1]);
			lazy[i] = 0;
		}
		if(la1[i] != 1){
			pushmul(e[i].son[0], la1[i]);
			pushmul(e[i].son[1], la1[i]);
			la1[i] = 1;
		}
		if(la2[i]){
			pushadd(e[i].son[0], la2[i]);
			pushadd(e[i].son[1], la2[i]);
			la2[i] = 0;
		}
	}
	
	inline bool get(int i){return e[e[i].fa].son[1] == i;}
	
	inline bool isrt(int i){return e[e[i].fa].son[0] != i && e[e[i].fa].son[1] != i;}
	
	inline void rotate(int x){
		int y = e[x].fa,z = e[y].fa,l,r;
		int k = l = get(x);
		r = l ^ 1;
		e[y].son[k] = e[x].son[k ^ 1];
		e[e[x].son[k ^ 1]].fa = y;
		e[x].son[k ^ 1] = y;
		if(!isrt(y))e[z].son[e[z].son[1] == y] = x;
		e[x].fa = z;
		e[y].fa = x;
		update(y),update(x);
	}
	
	inline void splay(int x){
		stack <int> q;
		q.push(x);
		for(int i = x;!isrt(i);)q.push(i = e[i].fa);
		while(!q.empty()){
			int v = q.top();
			q.pop();
			pushdown(v);
		}
		while(!isrt(x)){
			int y = e[x].fa,z = e[y].fa;
			if(!isrt(y)){
				if(get(x) == get(y))rotate(y);
				else rotate(x);
			}
			rotate(x);
		}
		update(x);
	}
	
	inline void access(int i){
		for(int t = 0;i;t = i,i = e[i].fa){
			splay(i);
			e[i].son[1] = t;
			update(i);
		}
	}
	
	inline void makert(int i){
		access(i);
		splay(i);
		pushrev(i);
	}
	
	inline int find(int i){
		access(i);
		splay(i);
		while(e[i].son[0])i = e[i].son[0];
		return i;
	}
	
	inline void split(int x,int y){
		makert(x);
		access(y);
		splay(y);
	}
	
	inline void cut(int x,int y){
		split(x,y);
		e[y].son[0] = e[x].fa = 0;
	}
	
	inline void link(int x,int y){
		makert(x);
		e[x].fa = y;
	}
}t;

signed main(){
	cin>>n>>m;
	for(int i = 1;i <= n;i ++)t.e[i].w = t.e[i].sum = t.e[i].siz = t.la1[i] = 1;
	for(int i = 1;i <= n - 1;i ++){
		int x,y;
		x = read(),y = read();
		t.link(x,y);
	}
	while(m --){
		char op;
		int x,y,xx,yy,w;
		scanf(" %c ",&op);
		x = read(),y = read();
		if(op == '+'){
			w = read();
			t.split(x,y);
			t.pushadd(y, w);
		}
		else if(op == '-'){
			xx = read(),yy = read();
			t.cut(x,y);
			t.link(xx,yy);
		}
		else if(op == '*'){
			w = read();
			t.split(x,y);
			t.pushmul(y,w);
		}
		else {
			t.split(x,y);
			printf("%lld\n",t.e[y].sum);
		}
	}
}

如上，全WA