n = input()

def nine(s):
    st = ""
    for _ in range(s):
        st += "9"
    return st


if int(n[0]) == 1:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 1)
        exit()
    else:
        print(9*(len(n) -1))
        exit()

if int(n[0]) == 2:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 2)
        exit()
    else:
        print(9*(len(n) -1) + 1)
        exit()

if int(n[0]) == 3:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 3)
        exit()
    else:
        print(9*(len(n) -1) + 2)
        exit()

if int(n[0]) == 4:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 4)
        exit()
    else:
        print(9*(len(n) -1) + 3)
        exit()

if int(n[0]) == 5:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 5)
        exit()
    else:
        print(9*(len(n) -1) + 4)
        exit()

if int(n[0]) == 6:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 6)
        exit()
    else:
        print(9*(len(n) -1) + 5)
        exit()

if int(n[0]) == 7:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 7)
        exit()
    else:
        print(9*(len(n) -1) + 6)
        exit()

if int(n[0]) == 8:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 8)
        exit()
    else:
        print(9*(len(n) -1) + 7)
        exit()

if int(n[0]) == 9:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 9)
        exit()
    else:
        print(9*(len(n) -1) + 8)
        exit()

### FIXED CODE ###

n = input()

def nine(s):
    st = ""
    for _ in range(s):
        st += "9"
    return st

if len(n) == 1:
    print(n)
    exit()

if int(n[0]) == 1:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 1)
        exit()
    else:
        print(9*(len(n) -1))
        exit()

if int(n[0]) == 2:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 2)
        exit()
    else:
        print(9*(len(n) -1) + 1)
        exit()

if int(n[0]) == 3:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 3)
        exit()
    else:
        print(9*(len(n) -1) + 2)
        exit()

if int(n[0]) == 4:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 4)
        exit()
    else:
        print(9*(len(n) -1) + 3)
        exit()

if int(n[0]) == 5:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 5)
        exit()
    else:
        print(9*(len(n) -1) + 4)
        exit()

if int(n[0]) == 6:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 6)
        exit()
    else:
        print(9*(len(n) -1) + 5)
        exit()

if int(n[0]) == 7:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 7)
        exit()
    else:
        print(9*(len(n) -1) + 6)
        exit()

if int(n[0]) == 8:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 8)
        exit()
    else:
        print(9*(len(n) -1) + 7)
        exit()

if int(n[0]) == 9:
    if int(n[1:]) >= int(nine(len(n) - 1)):
        print(9*(len(n) -1) + 9)
        exit()
    else:
        print(9*(len(n) -1) + 8)
        exit()