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