难道是树剖写丑了吗qwq为什么#13卡不过去啊

// luogu-judger-enable-o2
#include<bits/stdc++.h>
using namespace std;
const int MAXN=3e5+10;
const int MAXM=6e5+10;

int n,m,cnt,pts;
int s[MAXN],t[MAXN],lc[MAXN],len[MAXN],deep[MAXN];

const int RLEN=1<<18|1;
inline char nc() {
    static char ibuf[RLEN],*ib,*ob;
    (ib==ob) && (ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
    return (ib==ob) ? -1 : *ib++;
}
inline int Read() {
    char ch=nc(); int i=0,f=1;
    while(!isdigit(ch)) {if(ch=='-') f=-1; ch=nc();}
    while(isdigit(ch)) {i=(i<<1)+(i<<3)+ch-'0'; ch=nc();}
    return i*f;
}

inline void swap(int &x,int &y){
    int t=x;
    x=y,y=t;
}

namespace SLPF{
    int head[MAXN],depth[MAXN],siz[MAXN],fa[MAXN],son[MAXN],top[MAXN];
    int nxt[MAXM],to[MAXM],w[MAXM];
    int dfn[MAXN],tot;
    int a[MAXN],delta[MAXN];
    
    inline void init(){
        memset(head,-1,sizeof(head[0])*(pts+5));
    }

    inline void add(int x,int y,int z){
        nxt[cnt]=head[x];
        head[x]=cnt;
        to[cnt]=y;
        w[cnt]=z;
        cnt++;
    }
    
    void dfs1(int u,int f){
        siz[u]=1;
        for(int i=head[u];i!=-1;i=nxt[i]){
            int v=to[i];
            if(v==f)
              continue;
            a[v]=w[i];
            depth[v]=depth[u]+1;
            deep[v]=deep[u]+w[i];
            fa[v]=u;
            dfs1(v,u);
            siz[v]+=siz[u];
            if(siz[v]>siz[son[u]])
              son[u]=v;
        }
    }
    
    void dfs2(int u,int tp){
        top[u]=tp;
        dfn[u]=++tot;
        if(!son[u])
          return ;
        dfs2(son[u],tp);
        for(int i=head[u];i!=-1;i=nxt[i]){
            int v=to[i];
            if(v==fa[u]||v==son[u])
              continue;
            dfs2(v,v);
        }
    }
    
    inline int lca(int x,int y){
        while(top[x]!=top[y]){
            if(depth[top[x]]<depth[top[y]])
              swap(x,y);
            x=fa[top[x]];
        }
        return depth[x]<depth[y]?x:y;
    }
    
    void dfss(int u,int f){
        for(int i=head[u];i!=-1;i=nxt[i]){
            int v=to[i];
            if(v==f)
              continue;
            dfss(v,u);
            delta[u]+=delta[v];
        }
    }
    
    inline bool check(int x){
        int sum=0,ss=0;
        memset(delta,0,sizeof(delta[0])*(pts+5));
        for(int i=1;i<=m;++i){
            if(len[i]>x){
                sum++;
                ss=max(ss,len[i]-x);
                delta[s[i]]++;
                delta[t[i]]++;
                delta[lc[i]]-=2;
            }
        }
        dfss(1,-1);
        for(int i=1;i<=n;++i){
            if(delta[i]==sum&&a[i]>=ss)
              return 1;
        }
        return 0;
    }
}

int main(){
    int l=0,r=5e7+7;
    n=Read(),m=Read();
    pts=n+2;
    SLPF::init();
    for(int i=1;i<n;++i){
        int x=Read(),y=Read(),z=Read();
        SLPF::add(x,y,z),SLPF::add(y,x,z);
    }
    SLPF::dfs1(1,-1);
    SLPF::dfs2(1,1);
    for(int i=1;i<=m;++i)
      s[i]=Read(),t[i]=Read(),lc[i]=SLPF::lca(s[i],t[i]),len[i]=deep[s[i]]+deep[t[i]]-deep[lc[i]]*2,r=max(r,len[i]);;
    
    while(l<=r){
        int mid=l+r>>1;
        if(SLPF::check(mid))
          r=mid-1;
        else
          l=mid+1;
    }
    cout<<l;
    return 0;
}