import sys

try:
    import mydebug

    def dprint(*objects):
        print(*objects)
except:
    def dprint(*objects, sep='', end='\n'): pass

# d, p = [int(x) for x in input().split()]
# n = int(input())
s = input()

ans = 0

for i in range(len(s)):
    try:
        num = int(s[i])
        ans += num
    except:
        pass

print(ans)