s = eval(input())

print((s.count("1")))
def main():

    S = eval(input())

    print((sum(1 if s == "1" else 0 for s in S)))





if __name__ == '__main__':

    main()

s = eval(input())
print((s.count("1")))

def main():
    S = eval(input())
    print((sum(1 if s == "1" else 0 for s in S)))


if __name__ == "__main__":
    main()

-s = eval(input()) -print((s.count("1"))) +def main(): +    S = eval(input()) +    print((sum(1 if s == "1" else 0 for s in S))) + + +if __name__ == "__main__": +    main()