#!/usr/local/bin/python3
def dt(M,n):
 M=[r[:] for r in M];r=0
 for c in range(n):
  p=next((i for i in range(r,n) if M[i][c]),-1)
  if p<0:continue
  M[r],M[p]=M[p],M[r]
  for i in range(r+1,n):
   if M[i][c]:
    for j in range(c,n):M[i][j]^=M[r][j]
  r+=1
 return r==n
def iv(M,n):
 A=[M[i][:]+[int(i==j) for j in range(n)] for i in range(n)];r=0
 for c in range(n):
  p=next((i for i in range(r,n) if A[i][c]),-1)
  if p<0:return None
  A[r],A[p]=A[p],A[r]
  for i in range(n):
   if i!=r and A[i][c]:
    for j in range(c,2*n):A[i][j]^=A[r][j]
  r+=1
 return [q[n:] for q in A]
def br(n):
 E=[(i,j) for i in range(n) for j in range(i+1,n)];c=0
 for m in range(1<<len(E)):
  A=[[0]*n for _ in range(n)]
  for k,(i,j) in enumerate(E):
   if m>>k&1:A[i][j]=A[j][i]=1
  if dt(A,n):
   B=[r[:] for r in A]
   for i in range(n):B[i][i]^=1
   if dt(B,n):
    C=iv(B,n)
    if all(C[i][i]==(i<2) for i in range(n)):c+=1
 return c
print('n4',br(4))
print('n6',br(6))