a = int(input())
for i in range(100):
    if 2**i >= a:
        break
ans = 2*i

for i in range(100):
    if 3**i >= a:
        ans = min(3*i,ans)
        break

for i in range(100):
    if 5**i >= a:
        ans = min(5*i,ans)
        break

print(ans)