Problem:
Score : 100 points

Problem Statement

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?

Constraints

The length of S is 6.

S consists of 0 and 1.

Inputs

Input is given from Standard Input in the following format:

S

Outputs

Print the number of problems prepared by Snuke that are accepted to be used in the contest.

Sample Input 1

111100

Sample Output 1

4

The first, second, third and fourth problems are accepted, for a total of four.

Sample Input 2

001001

Sample Output 2

2

Sample Input 3

000000

Sample Output 3

0

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
#include <limits>
#include <cstdlib>
#include <regex>
using namespace std;

double inf = numeric_limits<double>::infinity();

#define REP(i,n) for(int i=0;i<n;i++)
using LL = long long int;
LL GCD(LL a,LL b){ if(a<b) return GCD(b,a); else if(a%b==0) return b; else return GCD(b,a%b); }
LL LCM(LL a,LL b){ return (a/GCD(a,b))*b; }


int main() {
    string s;
    cin >> s;
    int cnt = 0;
    REP(i,6) {
        if (s[i] == '1') cnt++;
    }
    
    cout << cnt << endl;
}