# coding utf-8
# https://yukicoder.me/plobrems/no/656
score = int(input())
score_a = [int(x) for x in list(str(score))]
sum = 0
for i in range(len(score_a)):
    if score_a[i] == 0:
       sum += 10
    else:
        sum += int(score_a[i])
print(sum)