t,r = map(int,input().split())
p = 1
for _ in range(n):
    n,*S = map(int,input().split())
    L = []
    stack = []
    for _,i in sorted([(s,i) for i,s in enumerate(S,p)]):
        stack.append(i)
        if len(stack) == 4:
            for j in range(3):
                L.append(stack[j],stack[j+1])
            stack.clear()
    for j in range(len(stack)-1):
        L.append(stack[j],stack[j+1])
    print(len(L),flush=True)
    for u,v in L:
        print(u,v,flush=True)
    p += n