#include<bits/stdc++.h>
using namespace std;
long long int dis[100000],d,aaa;
struct point
{
    long long int name,val,road;
    bool operator<(const point &a)const
    {
        return a.val<val;
    }
};
struct node
{
    long long int mm,nn,oo;
};
vector<node>mp[100000];
vector<node>::iterator u;
void dijkstra(point dublin)
{
    priority_queue<point>pq;
    pq.push(dublin);
    while(!pq.empty())
    {
        point temp;
        temp=pq.top();
        pq.pop();
        if(temp.name==(aaa-1))
        {
            break;
        }
        long long int aa,b,c,x,z,y;
        node r;
        aa=temp.name;
        b=temp.val;
        c=temp.road;
        for(u=mp[aa].begin(); u!=mp[aa].end(); u++)
        {
            r=*u;
            x=r.mm;
            y=r.nn;
            z=r.oo;
            if(c+z<=d)
            {
                point zenit;
                zenit.name=x;
                zenit.val=b+y;
                zenit.road=c+z;
                dis[x]=min(dis[x],b+y);
                pq.push(zenit);
            }

        }
    }

}
int main ()
{
    //freopen("in.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    long long int n,i,b,c,j,x,y,z;
    cin>>n;
    for(i=1; i<=n; i++)
    {
        cin>>aaa>>b>>c>>d;
        for(j=1; j<=b; j++)
        {
            cin>>x>>y>>z;
            node tata;
            tata.mm=y;
            tata.nn=z;
            tata.oo=0;
            mp[x].push_back(tata);
        }
        for(j=1; j<=c; j++)
        {
            cin>>x>>y>>z;
            node tata;
            tata.mm=y;
            tata.nn=z;
            tata.oo=1;
            mp[x].push_back(tata);
        }
        for(j=1; j<aaa; j++)
        {
            dis[j]=1e17;
        }
        point get;
        get.name=0;
        get.val=0;
        get.road=0;
        dijkstra(get);
        if(dis[aaa-1]==1e17)
        {
            cout<<"Case "<<i<<": ";
            cout<<"Impossible"<<endl;
        }
        else
        {
            cout<<"Case "<<i<<": ";
            cout<<dis[aaa-1]<<endl;
        }
        for(j=0; j<aaa; j++)
        {
            mp[j].clear();
        }
        memset(dis,0,sizeof(dis));
    }
}