#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {

    int n;
    cin >> n;
    if ( n < 0) n = -n;
    int sum = 0;
    while ( n ) {
        sum += n % 10;
        n /= 10;
    }
    cout << sum << endl;
    return 0;
}
// 64 位输出请用 printf("%lld")