#include<cstdio>

 #include<cstring>

 #include<algorithm>

 #define MAXN 210

 #define INF 2147483646

 using namespace std;

 int f[MAXN], Rank[MAXN];    //Rank长度

 int n, m, pos;

 struct Edge{

     int u, v, val;

     //按照val从小到大排列

     friend bool operator<(const Edge&a, const Edge&b){

         return a.val < b.val;

     }

 }arr[MAXN*MAXN];

 void init(){

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

         f[i] = i, Rank[i] = ;

 }

 int find(int x){

     int i, j = x;

     while (j != f[j]) j = f[j];

     while (x != j){

         i = f[x]; f[x] = j; x = i;

     }

     return j;

 }

 void Union(int x, int y){

     int a = find(x), b = find(y);

     if (a == b)return;

     if (Rank[a]>Rank[b])

         f[b] = a;

     else{

         if (Rank[a] == Rank[b])

             ++Rank[b];

         f[a] = b;

     }

 }

 int main(){

     int u, v, speed, Q;

     while (scanf("%d%d", &n, &m) != EOF){

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

             scanf("%d%d%d", &arr[i].u, &arr[i].v, &arr[i].val);

         sort(arr, arr + m);

         scanf("%d", &Q);

         while (Q--){

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

             int ans = INF;

             for (int j = ; j < m; ++j){

                 init();

                 for (int k = j; k < m; ++k){

                     Union(arr[k].u, arr[k].v);

                     if (find(u) == find(v)){

                         ans = min(ans, arr[k].val - arr[j].val);    //使ans尽可能的小

                         break;

                     }

                 }

             }

             if (ans == INF)

                 printf("-1\n");

             else

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

         }

     }

     //system("pause");

     return ;

 }