#include<bits/stdc++.h>
#define raed read
#define int long long 
using namespace std;
const int MAXN = 410,INF = 0x3f3f3f3f;
const double eps = 0.0001;
inline int read(){
	int X=0; bool flag=1; char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') flag=0; ch=getchar();}
	while(ch>='0'&&ch<='9') {X=(X<<1)+(X<<3)+ch-'0'; ch=getchar();}
	if(flag) return X;return ~(X-1);
}
int T,n,m,q,t,s,a[MAXN],b[MAXN],p[MAXN],dis[MAXN][MAXN];
int f[MAXN][MAXN];//上了i门课 当前在j时最多能睡多少 
signed main(){
	n = read(),m = raed(),q = raed(),t = raed(),s = raed();
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			dis[i][j] = INF;
		}
		dis[i][i] = 0;
	}
	for(int i=1;i<=m;i++){
		int u = raed(),v = read(),w = raed();
		dis[u][v] = min(f[u][v],w);
		dis[v][u] = min(dis[v][u],w);
	}
	vector<int> v;
	for(int i=1;i<=q;i++){
		int A = raed(),B = raed();
		p[i] = raed();
		a[p[i]] = A,b[p[i]] = B;
		v.push_back(p[i]);
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			for(int k=1;k<=n;k++){
				dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);
			}
		}
	}
	memset(f,-INF,sizeof(f));
	f[0][1] = 0;
	for(int i=1;i<=q;i++){
		for(auto j:v){
			for(int k=1;k<=n;k++){
				int d = dis[k][j];
				if(b[k]+d>a[j]||f[i-1][k]<0) continue;
				if(b[k]+dis[k][1]+dis[1][j]<=a[j]){
					f[i][j] = max(f[i][j],f[i-1][k]+(a[j]-(b[k]+dis[k][1]+dis[1][j])));
				}
				else f[i][j] = max(f[i][j],f[i-1][k]);
			}
		}
	}
	int i;
	for(i=q;i>=1;i--){
		bool check = 0;
		for(auto j:v){
			int now = f[i][j];
			if(t-b[j]-dis[j][1]>=0) now+=t-b[j]-dis[j][1];
			else continue;
			if(now>=s){
				check = 1;
				break;
			}
		}
		if(check) break;
	}
	cout<<i<<endl; 
}
/*
5 4 3 10 2
3 4 1
2 5 1
4 5 1
3 1 1
2 9 2
3 9 4
6 8 3
1
5 4 4 15 3
3 4 1
4 1 1
5 2 2
5 3 2
5 6 4
8 9 3
13 14 2
4 6 5
2
*/