1 #include <cstdio>
 2 #include <cstring>
 3 #define max(x,y) (x > y ? x : y)
 4 #define MAX 302
 5 #define INF 1000000000
 6 using namespace std;
 7 
 8 int dis[MAX][MAX],dp[MAX][MAX];
 9 int n,m;
10 
11 void flyod(){
12     for(int u=1;u<=n;u++){
13         for(int i=1;i<=n;i++){
14             for(int j=1;j<=n;j++){
15                 if(dis[i][j]>dis[i][u]+dis[u][j]){
16                     dis[i][j]=dis[i][u]+dis[u][j];
17                     dp[i][j]=dp[i][u]+dp[u][j];
18                 }else if(dis[i][j]==dis[i][u]+dis[u][j]){
19                     dp[i][j]=max(dp[i][u]+dp[u][j],dp[i][j]);
20                 }
21             }
22         }
23     }
24 }
25 
26 int main()
27 {
28     int a,b,l;
29     int s1,e1,s2,e2;
30     int ans;
31     //freopen("data.txt","r",stdin);
32     while(scanf("%d %d",&n,&m),(n+m)){
33         for(int i=1;i<=n;i++){
34             for(int j=1;j<=n;j++){
35                 dis[i][j]= i==j ? 0 : INF;
36                 dp[i][j]=0;
37             }
38         }
39         for(int i=0;i<m;i++){
40             scanf("%d %d %d",&a,&b,&l);
41             if(dis[a][b]>l){
42                 dis[a][b]=dis[b][a]=l;
43                 dp[a][b]=dp[b][a]=1;
44             }
45         }
46 
47         scanf("%d %d %d %d",&s1,&e1,&s2,&e2);
48         flyod();
49         ans=-1;
50         for(int i=1;i<=n;i++){
51             for(int j=1;j<=n;j++){
52                 if(dp[i][j]>ans && (dis[s1][e1] == dis[s1][i]+dis[i][j]+dis[j][e1])
53                 && (dis[s2][e2] == dis[s2][i]+dis[i][j]+dis[j][e2]) ){
54                     ans=dp[i][j];
55                 }
56             }
57         }
58         printf("%d\n",ans+1);
59     }
60     return 0;
61 }