n=int(input())
s=0
if n>=10 and n<=100:
    s=n*2
elif n<10 and n>0:
    s=n*2.2
print('%.1f' %s)


/**************************************************************
	Problem: 1303
	User: admin
	Language: Python
	Result: Accepted
	Time:93 ms
	Memory:34244 kb
****************************************************************/