X = int(input())
count = 0
i = 0
while i != X:
    i += 2
    count += 2
    if i == X:
        break
    i += 2
    count += 2
    if i == X:
        break
    i -= 1 
    count += 1
    if i == X:
        break
    i -= 1 
    count += 1 
    if i == X:
        break
    i += 2 
    count += 2 
    if i == X:
        break
    i -= 1 
    count += 1 
    if i == X:
        break 
    i -= 1 
    count += 1 
    if i == X:
        break
print(count)