#include 
#include 
#include 
#include 
using namespace std;

int rec(int x) {
    if(x == 0) {
        return 0;
    }
    
    int cifra = x % 10;
    return cifra + rec(x / 10);
}
int main()
{
    
    cout << rec(1234) << endl;
  
    return 0;
}
// rek(1234) = 4 + rec(123) = 4 + 6 = 10
// rec(123) = 3 + rec(12) = 3 + 3 = 6
// rec(12) = 2 + rec(1) = 2 + 1 = 3
// rec(1) = 1 + rec(0) = 1 + 0 = 1
// rec(0) = 0