#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>
using namespace std;
int n,m,a,b,c;
vector<int>A[20010];
vector<int>C[20010];
queue<int>q; 
int vis[20010]={0},dis[20010];
void spfa(int f)
{
	memset(dis,127/2,sizeof(dis));
	dis[f]=0;
	vis[f]=1;
	q.push(f);
	while(!q.empty())
	{
		int cc=q.front();
		q.pop();
		vis[cc]=0;
		for(int i=0;i<A[cc].size();i++)
		{
			int u=A[cc][i];
			if(dis[u]>dis[cc]+C[cc][i])
			{
				dis[u]=dis[cc]+C[cc][i];
				if(!vis[u])
				{
					vis[u]=1;
					q.push(u);
				}
			}
		}
	}
}
int main()
{
	freopen("distance.in","r",stdin);
	freopen("distance.out","w",stdout);
	cin>>n>>m;
	for(int i=1;i<n;i++)
	{
		cin>>a>>b>>c;
		A[a].push_back(b);
		A[b].push_back(a);
		C[a].push_back(c);
		C[b].push_back(c);
	}
	int f,g;
	for(int i=1;i<=m;i++)
	{
		cin>>f>>g;
		spfa(f);
		cout<<dis[g]<<endl;
	}
	return 0;
}