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 <bits/stdc++.h>
using namespace std;
//make_tuple emplace_back next_permutation push_back make_pair second first setprecision

#if MYDEBUG
#include "lib/cp_debug.h"
#else
#define DBG(...) ;
#endif

using LL = long long;
constexpr LL LINF=334ll<<53;
constexpr int INF=15<<26;
constexpr LL  MOD=1E9+7;

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    string s;
    cin >> s;
    int ans=0;
    for(int i=0; i<6; ++i){
        if(s[i]=='1')ans++;
    }
    cout << ans <<endl;
    return 0;
}