#include<iostream>
#include<fstream>
#include<vector>
#define first f
#define second s
#define make_pair mp
#define push_back pb
using namespace std;
void bfs()
{
	viz[x]=1;
	t=0;
	while(t<n)
	{
		
		
		
	}
	
	
	
	
}




int main()
{
	cin>>n>>m>>x>>y;
	for(i=0;i<m;++i)
	{
		cin>>a>>b>>c;
		A[a].pb(mp(b,c));
		A[b].pb(mp(a,-c));
	}
	bfs();
	
	
}