n = int(input().strip())
ls = [
    1000000001,
    11000000011,
    111000000111,
    1111000001111,
    11111000011111,
    111111000111111,
    1111111001111111,
    11111111011111111,
    111111111111111111,
]
total = 0
for a in ls:
    x = a
    for _ in range(9):
        if n > x:
            total += 1
            x += a
        else:
            print(total)
            raise SystemExit
print(total)