#include <iostream>
#include <cmath>
using namespace std;

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