hdu 1598

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
#define N 1005
#define INF 0x1f1f1f1f
struct 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;
}