n=int(input())
tong=45
s=n%10
x=n//10
if n<10:
print((n+1)n//2)
else:
tong+=((s+1)s//2)+((s+1)(n//10))
if n>=20:
tong+=+55(x-1)
print(tong)

Lê Hiếu 10TH