import math

def f(i,j):
    if i==-1:
        return False
    if i==j:
        return True
    ct=0

    for k in range(5):
        if r[i][k]<r[j][k]:
            ct+=1
    
    return ct>=3


T=int(input())
# T=1
for __ in range(T):
    n=int(input())
    r=[]
    for i in range(n):
        tmp=list(map(int,input().split()))
        r.append(tmp)
    # print(r)
    mx=-1

    for i in range(n):
        if f(mx,i):
            continue
        else:
            mx=i
    
    fg=True
    for i in range(n):
        if f(mx,i):
            continue
        else:
            fg=False
    
    if fg:
        print(mx+1)

        continue
    print(-1)