Snuke prepared 6 problems for a upcoming programming contest. For each of those problems, Rng judged whether it can be used in the contest or not.  You are given a string S of length 6. If the i-th character of s is `1`, it means that the i-th problem prepared by Snuke is accepted to be used; `0` means that the problem is not accepted.  How many problems prepared by Snuke are accepted to be used in the contest?
111100
#!/usr/bin/env python3

S = str(input())

total = 0
for i in S:
    if i == "1":
        total += 1

print(total)