#include <bits/stdc++.h>

using namespace std;
ifstream fin("sate.in");
ofstream fout("sate.out");
vector <pair<int,int>> v[100005];
queue <int> q;
int n,m,s1,s2,d[100005],ans;
void bfs(int st)
{
    d[st]=1;
    q.push(st);
    while (!q.empty())
    {
        int nod=q.front();
        for (auto i : v[nod])
        {
            int nextnod=i.first,dist=i.second;
            if (!d[nextnod])
            {
                if (nod>nextnod) ans-=dist;
                    else ans+=dist;
                d[nextnod]=1;
                cout<<i.first<<' '<<dist<<'\n';
                q.push(nextnod);
            }
        }
        q.pop();
    }
}
int main()
{
    fin>>n>>m>>s1>>s2;
    for (int i=1;i<=m;i++)
    {
        int a,b,dist;
        fin>>a>>b>>dist;
        v[a].push_back({b,dist});
        v[b].push_back({a,dist});
    }
    bfs(s1);
    fout<<ans;
    return 0;
}