def f(l,r):
    return list(range(l,r+1))

#==================================================
N=int(input())
#==================================================
A=[]

A.append(f(N,2*N-1))
A.append(f(N,2*N-1))

for i in range(1,N):
    A.append(f(i,i)+f(N+1,2*N-1))

for i in range(2,N):
    A.append(f(i,N)+f(2*N+1-i,2*N-1))

print(2*N-1)
for a in A:
    print(*a)