#include<bits/stdc++.h>
using namespace std;
const int N=3e5+10;
int n,m,fa[N],dep[N],son[N],top[N],sum[N],sz[N],st[N],en[N],temp[N],dfn[N];
vector<pair<int,int> > e[N];
void dfs(int x,int deep,int father,int val)
{
	sz[x]=1,dep[x]=deep,fa[x]=father,sum[x]=val;
	for(auto v:e[x])
	{
		int u=v.first,w=v.second;
		if(u==fa[x]) continue;
		dfs(u,deep+1,x,val+w);
		sz[x]+=sz[u];
		if(sz[u]>sz[son[x]]) son[x]=u;
	}
}
int tot;
void dfs1(int x,int k)
{
	dfn[++tot]=x;
	if(son[x]) dfs1(son[x],k);
	top[x]=k;
	for(auto v:e[x])
	{
		int u=v.first;
		if(u==son[x]||u==fa[x]) continue;
		dfs1(u,u);
	}
}
int lca(int x,int y)
{
	for(;top[x]!=top[y];)
	{
		if(dep[top[x]]<dep[top[y]]) swap(x,y);
		x=fa[top[x]];
	}
	return (dep[x]<dep[y])?x:y;
}
bool check(int x)
{
	int sm=0,maxx=0;
	memset(temp,0,sizeof temp);
	for(int i=1;i<=m;i++)
	{
		int LCA=lca(st[i],en[i]);
		if(sum[st[i]]+sum[en[i]]-2*sum[LCA]<=x) continue; 
		maxx=max(maxx,sum[st[i]]+sum[en[i]]-2*sum[LCA]-x);
		temp[st[i]]++,temp[en[i]]++;
		temp[LCA]-=2;
		sm++;
	}
	if(!sm) return true;
	for(int i=n;i>1;i--) temp[fa[dfn[i]]]+=temp[dfn[i]];
	for(int i=1;i<=n;i++)
	{
		if(temp[dfn[i]]>=sm&&sum[dfn[i]]-sum[fa[dfn[i]]]>=maxx) return true;
	}
	return false;
}
int f(int l,int r)
{
	if(l>=r) return l;
	int mid=l+r>>1;
	if(check(mid)) return f(l,mid);
	return f(mid+1,r);
}
int main()
{	
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	int sm=0;
	for(int i=1;i<n;i++) 
	{
		int x,y,z;
		cin>>x>>y>>z;
		e[x].push_back({y,z});
		e[y].push_back({x,z});
		sm+=z;
	}
	for(int i=1;i<=m;i++) cin>>st[i]>>en[i];
	dfs(1,1,0,0);
	dfs1(1,1);
	cout<<f(0,sm);
	return 0;
}