#include <stdio.h>#include <string.h>#include <algorithm>using namespace std;#define N 1005#define INF 0x1f1f1f1fstruct tt{    int x,y,sp;}p[N];int pre[N];bool cmp(tt a, tt b){    return a.sp<b.sp;}int find(int x){    int r = x;    while(x!=pre[x]) x = pre[x];    while(r!=x)    {        int j = pre[r];        pre[r] = x;        r = j;    }    return x;}int main(){    int n,q,i,j,s,t,m;    while(~scanf("%d %d",&n,&m))    {        for(i = 0 ; i < m ; i++)            scanf("%d %d %d",&p[i].x,&p[i].y,&p[i].sp);        sort(p,p+m,cmp);        scanf("%d",&q);        while(q--)        {   int minx = INF;            scanf("%d %d",&s,&t);            for(i = 0 ; i < m ; i++)            {                for(j = 0 ; j <= n ; j++) pre[j] = j;                for(j = i ; j < m ; j++)                {                    int fx = find(p[j].x);                    int fy = find(p[j].y);                    if(fx!=fy) pre[fx] = fy;                    if(find(s) == find(t)) minx = min(minx,p[j].sp - p[i].sp);                }            }            if(minx!=INF) printf("%d\n",minx);            else printf("-1\n");        }    }    return 0;}