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>
#include <boost/multiprecision/cpp_int.hpp>
using namespace std;
typedef long long ll;
namespace mp = boost::multiprecision;
using Mint = mp::cpp_int;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repi(i,a,b) for(int i = int(a); i < int(b); i++)
#define all(v) v.begin(), v.end()
#define uni(v) v.erase(unique(all(v)), v.end())
#define sort_g(v) sort(all(v), greater<int>())
#define dump(x) cerr << #x << ' ' << '=' << ' ' << x << endl

int main() {
    string S;
    cin >> S;
    int cnt = 0;
    for(char c : S) {
        if(c == '1') cnt++;
    }
    cout << cnt << endl;
}