import heapq

N = int(input())

heap = [(-k, k) for k in range(2 * N - 1, 0, -1)]
heapq.heapify(heap)

result = []
while len(heap) >= 3:
    c1, v1 = heapq.heappop(heap)
    c2, v2 = heapq.heappop(heap)
    c3, v3 = heapq.heappop(heap)

    result.append((v1, v2, v3))
    
    if c1 != -1:
        heapq.heappush(heap, (c1 + 1, v1))
    if c2 != -1:
        heapq.heappush(heap, (c2 + 1, v2))
    if c3 != -1:
        heapq.heappush(heap, (c3 + 1, v3))


print(len(result))
for row in result:
    print(*row)