"""

"""

from sys import stdin

T,R = map(int,stdin.readline().split())
p = 1

for loop in range(T):

    NS = list(map(int,stdin.readline().split()))
    #print (0,flush=True)

    
    N = NS[0]
    S = NS[1:]

    Si = [(S[i],i+p) for i in range(N)]
    p += N

    Si.sort()

    npl = []
    for j in range(N-1):
        if j % 4 != 3:
            l = Si[j][1]
            r = Si[j+1][1]
            npl.append(str(l)+ " "+str(r))

    print (len(npl))
    print ("\n".join(npl),flush=True)