import sys
if sys.platform =='ios':
	import clipboard
	a=clipboard.get()
	a = a.split('\n')
	text = '\n'.join(a)
	with open('input_file.txt','w') as f:
		f.write(text)
	sys.stdin = open('input_file.txt')
	
n = int(input())
ans = 0
ans += (n//3)*2
ans += (n//5)*2
print(ans)