N=int(input())

NN=N*2-1

ans = [[] for _ in range(NN)]

j = 0
sn=1
for i in range(1,NN+1):
    cnt=i
    while cnt:
        cnt-=1
        ans[j].append(i)
        j+=sn
        if j>=NN:
            j-=1
            sn=-1
        elif j<0:
            j=0
            sn=1

print(len(ans))
for a in ans:print(*a)