#include<bits/stdc++.h>
using namespace std;
int test,n,m,k,x[11],y[11],z[11],l,r,mid,msk,num[66],sum[66],cc;
bool check()
{
    memset(num,0,sizeof(num));memset(sum,0,sizeof(sum));
    for (int i=1;i<=n;i++)
    {
        for (int j=1;j<=m;j++)
        {
            msk=0;
            for (int h=0;h<k;h++)
            {
                if (abs(i-x[h])+abs(j-y[h])<=mid) msk|=(1<<h);
            }
            num[msk]++;
        }
    }
    for (int i=0;i<(1<<k);i++)
    {
        for (int j=0;j<(1<<k);j++)
        {
            if ((i&j)==j) sum[i]+=num[j];
        }
        cc=0;
        for (int j=0;j<k;j++)
        {
            if (i&(1<<j)) cc+=z[j];
        }
        if (cc<sum[i]) return 0;
    }
    return 1;
}
int main()
{
    scanf("%d",&test);
    while(test--)
    {
        scanf("%d%d%d",&n,&m,&k);
        for (int i=0;i<k;i++)
        {
            scanf("%d%d%d",&x[i],&y[i],&z[i]);
        }
        l=0;r=2000;
        while(l<=r)
        {
            mid=(l+r)>>1;
            if (check()) r=mid-1;
            else l=mid+1;
        }
        if (l==2001)  printf("-1\n");
        else printf("%d\n",l);
    }
    return 0;
}