ARPZ_s1_pr4/alg_4_4.cpp

#include <iostream>
using namespace std;

int f(int n, int sum)
{
	if (n == 0)
	{
		return sum;
	}
	return f(n / 10, sum + n % 10);
}

int main()
{
	int n; cin >> n;

	cout << f(n, 0);
}