1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstdio>
 4 #include<cstring>
 5 #include<cmath>
 6 using namespace std;
 7 const int INF=0x7f7f7f7f;
 8 const int MAXN=210;
 9 const int MAXM=1010;
10 int pre[MAXN];
11 struct Node{
12     int u,v,d;
13 };
14 Node dt[MAXM];
15 int cmp(Node a,Node b){
16     return a.d<b.d;
17 }
18 int find(int x){
19     int r=x;
20     while(r!=pre[r])r=pre[r];
21 //    pre[x]=r;
22     return r;
23 }
24 int main(){
25     int n,m;
26     while(~scanf("%d%d",&n,&m)){
27         for(int i=0;i<m;i++){
28             scanf("%d%d%d",&dt[i].u,&dt[i].v,&dt[i].d);
29         }
30         sort(dt,dt+m,cmp);
31         int Q,s,e,f1,f2;
32         scanf("%d",&Q);
33         while(Q--){
34             int ans=INF;//这个竟然被我写到外边 
35             scanf("%d%d",&s,&e);
36             for(int j=0;j<m;j++){
37                 for(int i=1;i<=n;i++)pre[i]=i;
38             for(int i=j;i<m;i++){
39                 int u=dt[i].u,v=dt[i].v,d=dt[i].d;
40                 f1=find(u);f2=find(v);
41                 if(f1!=f2)pre[f2]=f1;
42                 if(find(s)==find(e)){
43                     ans=min(ans,d-dt[j].d);
44                     break;
45                 }
46             }
47         }
48         if(ans==INF)puts("-1");
49         else printf("%d\n",ans);
50         }
51     }
52     return 0;
53 }