S=input()
ans=0
for i in range(len(S)):
    if S[i]=="1":
        ans+=1
    elif S[i]=="2":
        ans+=2
    elif S[i]=="3":
        ans+=3
    elif S[i]=="4":
        ans+=4
    elif S[i]=="5":
        ans+=5
    elif S[i]=="6":
        ans+=6
    elif S[i]=="7":
        ans+=7
    elif S[i]=="8":
        ans+=8
    elif S[i]=="9":
        ans+=9
print(ans)