def solve():
    n = int(input())
    ans = 0
    num = 10 ** 9 + 1
    for i in range(len(str(n // (10 ** 9)))):
        for j in range(1, 10):
            if num * int(str(j) * (i + 1)) <= n:
                ans += 1
            else:
                break
    print(ans)

if __name__=="__main__":
    solve()