#include <fstream>
#include <vector>
using namespace std;
ifstream f("sate.in");
ofstream g("sate.out");
int n,m,x,y;
bool viz[10001];
vector <pair<int,int> > a[10001];
void Citire()
{
    int x1,x2,x3;
    f>>n>>m>>x>>y;
    while(f>>x1>>x2>>x3)
    {
        a[x1].push_back(make_pair(x2,x3));
        a[x2].push_back(make_pair(x1,x3));
    }
}
void ParcAdan(int i,int cost)
{
    int nod;
    viz[i]=true;
    for(int k=0;k<a[i].size();k++)
    {
        nod=a[i][k].first;
        if(viz[nod]==false)
        {
            if(nod!=y)
        {
            if(i>nod)
        {
            cost-=a[i][k].second;
            ParcAdan(nod,cost);
            cost+=a[i][k].second;
        }
        else
        {
            cost+=a[i][k].second;
            ParcAdan(nod,cost);
            cost-=a[i][k].second;
        }
        }
        else
        {
            if(i>nod)
            {
                cost-=a[i][k].second;
            }
            else
            {
                cost+=a[i][k].second;
            }
            g<<cost;
        }
        }



    }
}
int main()
{
    Citire();
    if(x>y)
    {
        y=y+x;
        x=y-x;
        y=y-x;
    }
    ParcAdan(x,0);
    return 0;
}