S=input()
sum=0

for i in range(len(S)):
    if S[i] == '1':
        sum+=1

    elif S[i] == '2':
        sum+=2

    elif S[i] == '3':
        sum+=3

    elif S[i] == '4':
        sum+=4

    elif S[i] == '5':
        sum+=5

    elif S[i] == '6':
        sum+=6

    elif S[i] == '7':
        sum+=7

    elif S[i] == '8':
        sum+=8

    elif S[i] == '9':
        sum+=9
    else:
        sum+=0

print(sum)