#include <iostream>
#include <stdio.h>
#include <math.h>
 
using namespace std;
 
int n,e,t,m,graph[101][101],a[101];
 
bool visited[101];
 
int dijkstra()
{
    int Min=30000,MinI;
 
    for(int i=1;i<=n;i++)
    {
        if(a[i]<Min&&visited[i]==false)
        {
            Min=a[i];
 
            MinI=i;
        }
    }
 
    if(MinI==e)
    {
        return 0;
    }
 
    visited[MinI]=true;
 
    for(int i=1;i<=n;i++)
    {
        if(graph[MinI][i]>-1)
        {
            a[i]=min(a[i],a[MinI]+graph[MinI][i]);
        }
    }
 
    dijkstra();
 
    return 0;
}
 
int main()
{
    //freopen("input.txt","r",stdin);
 
    cin >> n >> e >> t >> m;
 
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=n;j++)
        {
            graph[i][j]=-1;
        }
    }
 
    int x,y,temp;
 
    while(m--)
    {
        scanf("%d %d %d",&x,&y,&temp);
 
        graph[x][y]=temp;
    }
 
    int ans=0;
 
    for(int i=1;i<=n;i++)
    {
        for(x=1;x<=n;x++)
        {
            visited[x]=false;
 
            a[x]=30000;
        }
 
        a[i]=0;
 
        dijkstra();
 
        if(a[e]<=t)
        {
            ans++;
        }
    }
 
    cout << ans << endl;
 
    return 0;
}

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4 
2 
1
8
1 2 1
1 3 1
2 1 1
2 4 1
3 1 1
3 4 1
4 2 1
4 3 1