#include<cstdio>

 #include<cstring>

 #include<algorithm>

 using namespace std;

 const int MAXN=;

 const int INF=0x7fffffff;

 struct Edge{

       int u,v,c;

       Edge(){}

       Edge(int _u,int _v,int _c):u(_u),v(_v),c(_c){}

 }edge[MAXN];

 int n,m;

 int p[];

 int cmp(Edge a,Edge b)

 {

       return a.c<b.c;

 }

 void init()

 {

       for(int i=;i<=n;i++)

             p[i]=i;

 }

 int find(int x)

 {

       return p[x]==x?x:p[x]=find(p[x]);

 }

 int main()

 {

       while(~scanf("%d%d",&n,&m))

       {

             for(int i=;i<m;i++)

             {

                   int u,v,c;

                   scanf("%d%d%d",&u,&v,&c);

                   edge[i]=Edge(u,v,c);

             }

             sort(edge,edge+m,cmp);

             int q;

             scanf("%d",&q);

             while(q--)

             {

                   int mi=INF,a,b;

                   scanf("%d%d",&a,&b);

                   for(int i=;i<m;i++)

                   {

                         init();

                         int j;

                         for(j=i;j<m;j++)

                         {

                               int u=edge[j].u;

                               int v=edge[j].v;

                               int x=find(u);

                               int y=find(v);

                               if(x!=y)

                                     p[x]=y;

                               if(find(a)==find(b))

                                     break;

                         }

                         if(j==m)

                               break;

                         mi=min(mi,edge[j].c-edge[i].c);

                   }

                   if(mi==INF)

                         printf("-1\n");

                   else

                         printf("%d\n",mi);

             }

       }

       return ;

 }