讲真，为啥 C 会 RE 啊/kel

#include<stdio.h>
#include<ctype.h>
#include<string.h>
typedef int ll;
typedef long long int li;
#define MAXN 10051
#define max(x,y) (x)>(y)?(x):(y)
struct Edge{
	ll to,prev,dist;
};
struct SegmentTree{
	ll l,r,mx;
};
struct Edge ed[MAXN<<1];
struct SegmentTree tree[MAXN<<2];
ll test,n,tot,totd,u,v,swp;
ll last[MAXN],fa[MAXN],depth[MAXN],hv[MAXN],sz[MAXN],dfn[MAXN];
ll x[MAXN],top[MAXN],val[MAXN],from[MAXN],to[MAXN],dist[MAXN];
char ch[10];
ll read()
{
    register ll num=0,neg=1;
    register char ch=getchar();
    while(!isdigit(ch)&&ch!='-')
    {
        ch=getchar();
    }
    if(ch=='-')
    {
        neg=-1;
        ch=getchar();
    }
    while(isdigit(ch))
    {
        num=(num<<3)+(num<<1)+(ch-'0');
        ch=getchar();
    }
    return num*neg;
}
void addEdge(ll from,ll to,ll dist)
{
	ed[++tot].prev=last[from];
	ed[tot].to=to;
	ed[tot].dist=dist;
	last[from]=tot;
}
void dfs(ll node,ll f)
{
	ll mx=-1;
	sz[node]=1,depth[node]=depth[fa[node]=f]+1;
	for(register int i=last[node];i;i=ed[i].prev)
	{
		if(ed[i].to!=f)
		{
			dfs(ed[i].to,node),sz[node]+=sz[ed[i].to];
			sz[ed[i].to]>mx?mx=sz[hv[node]=ed[i].to]:1;
		}
	}
}
void dfs2(ll node,ll link)
{
	ll v;
	dfn[node]=++totd,val[totd]=x[node],top[node]=link;
	if(!hv[node])
	{
		return;
	}
	dfs2(hv[node],link);
	for(register int i=last[node];i;i=ed[i].prev)
	{
		(v=ed[i].to)!=fa[node]&&v!=hv[node]?dfs2(v,v):(void)(1);
	}
}
#define ls node<<1
#define rs node<<1|1
void update(ll node)
{
	tree[node].mx=max(tree[ls].mx,tree[rs].mx);
}
void create(ll l,ll r,ll node)
{
	tree[node].l=l,tree[node].r=r;
	if(l==r)
	{
		return (void)(tree[node].mx=val[l]);
	}
	ll mid=(l+r)>>1;
	create(l,mid,ls),create(mid+1,r,rs),update(node);
}
void change(ll pos,ll val,ll node)
{
	if(tree[node].l==tree[node].r)
	{
		return (void)(tree[node].mx=val);
	}
	ll mid=(tree[node].l+tree[node].r)>>1;
	change(pos,val,pos<=mid?ls:rs),update(node);
}
ll queryMax(ll l,ll r,ll node)
{
	if(l<=tree[node].l&&r>=tree[node].r)
	{
		return tree[node].mx;
	}
	ll mid=(tree[node].l+tree[node].r)>>1;
	return max((l<=mid?queryMax(l,r,ls):0),(r>mid?queryMax(l,r,rs):0));
}
#undef ls
#undef rs
ll query(ll x,ll y)
{
	ll res=0;
	while(top[x]!=top[y])
	{
		depth[top[x]]<depth[top[y]]?(swp=x,x=y,y=swp):1;
		res=max(res,queryMax(dfn[top[x]],dfn[x],1)),x=fa[top[x]];
	}
	depth[x]>depth[y]?(swp=x,x=y,y=swp):1;
	return max(res,queryMax(dfn[x]+1,dfn[y],1));
}
void solve()
{
	n=read();
	for(register int i=0;i<n-1;i++)
	{
		from[i]=read(),to[i]=read(),dist[i]=read();
		addEdge(from[i],to[i],dist[i]),addEdge(to[i],from[i],dist[i]);
	}
	dfs(1,0);
	for(register int i=0;i<n;i++)
	{
		depth[from[i]]>depth[to[i]]?(swp=from[i],from[i]=to[i],to[i]=swp):1;
		x[to[i]]=dist[i];
	}
	dfs2(1,1),create(1,n,1);
	while(scanf("%s",ch)==1)
	{
		if(ch[0]=='D')
		{
			return (void)(tot=totd=0,memset(last,0,sizeof(last)));
		}
		u=read(),v=read();
		ch[0]=='C'?change(dfn[to[u-1]],v,1):(void)printf("%d\n",query(u,v));
	}
}
int main()
{
	test=read();
	for(register int i=0;i<test;i++)
	{
		solve();
	}
}