题目描述
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.
输入格式
见题面
输出格式
见题面
样例输入
101
样例输出
2