Snuke has a grid consisting of three squares numbered 1, 2 and 3.
In each square, either 0 or 1 is written. The number written in Square i is s_i.
Snuke will place a marble on each square that says 1.
Find the number of squares on which Snuke will place a marble.

-----Constraints-----
 - Each of s_1, s_2 and s_3 is either 1 or 0.

-----Input-----
Input is given from Standard Input in the following format:
s_{1}s_{2}s_{3}

-----Output-----
Print the answer.

-----Sample Input-----
101

-----Sample Output-----
2

 - A marble will be placed on Square 1 and 3.

Source: atcoder | Difficulty: EASY


Solutions:
s = input()
count = 0
for i in range(len(s)):
	if s[i] == '1':
		count += 1
print(count)


a = input()
print(a.count('1'))


s = input()
number = '1'
count = s.count(number)
print(count)


print(input().count('1'))


cnt = 0
for s in input():
	if int(s) == 1:
		cnt += 1
print(cnt)


import bisect, collections, copy, heapq, itertools, math, string
import sys

def I():
	return int(sys.stdin.readline().rstrip())

def LI():
	return list(map(int, sys.stdin.readline().rstrip().split()))

def S():
	return sys.stdin.readline().rstrip()

def LS():
	return list(sys.stdin.readline().rstrip().split())
x = S()
count = 0
for s in x:
	if s == '1':
		count += 1
print(count)


s = input()
print(s.count('1'))


s = list(map(int, input()))
count = 0
for i in range(len(s)):
	if s[i] == 1:
		count += 1
print(count)


a = input()
count = 0
for i in a:
	if i == '1':
		count += 1
	else:
		pass
print(count)


print(sum([int(ss) for ss in input()]))


(s1, s2, s3) = list(map(str, input()))
counter = 0
if s1 == '1':
	counter += 1
if s2 == '1':
	counter += 1
if s3 == '1':
	counter += 1
print(counter)


m = 0
for s in list(input()):
	if int(s) == 1:
		m += 1
print(m)


S = input()
count = 0
if S[0] == '1':
	count += 1
if S[1] == '1':
	count += 1
if S[2] == '1':
	count += 1
print(count)


S = input()
print(S.count('1'))


s = list(input())
ans = 0
for i in range(len(s)):
	if s[i] == '1':
		ans += 1
else:
	print(ans)


st_list = list(input())
nu_list = [int(v) for v in st_list]
count = 0
for i in range(len(nu_list)):
	if nu_list[i] == 1:
		count += 1
print(count)


n = input()
result = sum(list(map(int, str(n))))
print(result)


s = input()
count = 0
for i in range(0, 3, 1):
	if s[i] == '1':
		count = count + 1
print(count)


cnt_1 = 0
list_S = input()
for i in list_S:
	if i == '1':
		cnt_1 += 1
print(cnt_1)


s = input()
s_c = s.count('1')
print(s_c)


s = input()
s1 = int(s[0])
s2 = int(s[1])
s3 = int(s[2])
print(s1 + s2 + s3)


a = str(input())
count = 0
for i in range(3):
	if a[i - 1] == '1':
		count += 1
print(count)


s = input()
ans = 0
for i in range(3):
	if s[i] == '1':
		ans += 1
print(ans)


s = input()
ans = 0
for i in s:
	ans += int(i)
print(ans)


import sys
sys.setrecursionlimit(10 ** 6)
s = list(str(input()))
ans = [1 if i == '1' else 0 for i in s]
print(sum(ans))


a = input()
x = 0
for i in range(3):
	if a[i] == '1':
		x = x + 1
print(x)


b = input()
a = str(b)
i = 0
if a[0] == '1':
	i += 1
if a[1] == '1':
	i += 1
if a[2] == '1':
	i += 1
print(i)


s = list(map(int, input()))
count = 0
for n in s:
	if n == 1:
		count += 1
print(count)


s = input()
(a, b, c) = (int(s[0]), int(s[1]), int(s[2]))
count = 0
if a == 1:
	count += 1
if b == 1:
	count += 1
if c == 1:
	count += 1
print(count)


number = list(map(int, input()))
a = 0
for i in number:
	if i == 1:
		a = a + 1
print(a)


s = input()
if s == '111':
	print(3)
elif s == '110' or s == '101' or s == '011':
	print(2)
elif s == '100' or s == '010' or s == '001':
	print(1)
else:
	print(0)


n = input()
print(n.count('1'))


s = str(input())
print(s.count('1'))


getints = lambda : list(map(int, input().split()))
s = input()
ans = 0
for c in s:
	if c == '1':
		ans += 1
print(ans)


s = map(int, list(input()))
print(sum(s))


a = int(input())
count = 0
if int(a / 100) == 1:
	count += 1
if int(a / 10 % 10) == 1:
	count += 1
if int(a % 100 % 10) == 1:
	count += 1
print(count)


li = list(input())
c = 0
for i in li:
	if i == '1':
		c += 1
print(c)


s = str(input())
ans = int(s[0]) + int(s[1]) + int(s[2])
print(ans)


s = list(input())
res = 0
for i in s:
	if i == '1':
		res += 1
print(res)


A = input()
ans = int(0)
if A[0] == '1':
	ans = ans + 1
if A[1] == '1':
	ans = ans + 1
if A[2] == '1':
	ans = ans + 1
print(ans)


s = list(input())
cnt = 0
for item in s:
	if int(item) == 1:
		cnt = cnt + 1
print(cnt)


i = str(input())
(s1, s2, s3) = (int(i[0]), int(i[1]), int(i[2]))
print(int(s1 + s2 + s3))


D = input()
A = '1'
B = '11'
C = '101'
F = '111'
if F == D:
	print(3)
elif B in D:
	print(2)
elif C == D:
	print(2)
elif A in D:
	print(1)
else:
	print(0)


s = input()
cnt = 0
if s[0] == '1':
	cnt += 1
if s[1] == '1':
	cnt += 1
if s[2] == '1':
	cnt += 1
print(cnt)


(s1, s2, s3) = map(int, input())
number_list = [s1, s2, s3]
counter = 0
for i in range(len(number_list)):
	if number_list[i] == 1:
		counter += 1
print(counter)


s = list(input())
print(s.count('1'))


def __starting_point():
	s = input()
	count = 0
	for n in range(3):
		if s[n] == '1':
			count = count + 1
	print(count)
__starting_point()


a = input()
b = a.count('1')
print(b)


area = input()
print(area.count('1'))


def main():
	s = input()
	print(s.count('1'))
main()


def iroha():
	num = input()
	count = 0
	for i in num:
		if i == '1':
			count += 1
	print(count)

def __starting_point():
	iroha()
__starting_point()


s = input()
ans = 0
for i in s:
	if i == '1':
		ans += 1
print(ans)


s = input()
count = 0
if s[0] == '1':
	count += 1
if s[1] == '1':
	count += 1
if s[2] == '1':
	count += 1
print(count)


s = input()
print(int(s[0]) + int(s[1]) + int(s[2]))


def solve(s):
	count = 0
	if s[0] == '1':
		count += 1
	if s[1] == '1':
		count += 1
	if s[2] == '1':
		count += 1
	print(count)

def __starting_point():
	solve(input())
__starting_point()


data = list(input())
c = 0
for i in range(0, len(data)):
	if data[i] == '1':
		c = c + 1
print(c)


s = input()
cnt = sum([int(c) for c in s])
print(cnt)