S=input()
m=0
n=0
while n<len(S):
	if S[n]=="1":
		m+=1
	elif S[n]=="2":
		m+=2
	elif S[n]=="3":
		m+=3
	elif S[n]=="4":
		m+=4
	elif S[n]=="5":
		m+=5
	elif S[n]=="6":
		m+=6
	elif S[n]=="7":
		m+=7
	elif S[n]=="8":
		m+=8
	elif S[n]=="9":
		m+=9
	n+=1
print(m)