N = int(input())

print(2 * N - 1)
import heapq
q = [(-(i+1),i+1) for i in range(2 * N-1)]
heapq.heapify(q)
print(q)
for _ in range(2 * N - 1):
    ans = []
    tmp = []
    for j in range(N):
        n,index = heapq.heappop(q)
        ans.append(index)
        if n != -1:
            tmp.append((n+1,index))
    for i in ans:
        print(i,end = " ")
    print()
    for n,index in tmp:
        heapq.heappush(q,(n,index))