#include <iostream>
using namespace std;
int main()
{
int n, suma, cif, catul, rest, unitati, zeci, sute;
cin >> n;
if (n<10) cout << n;
else
{
if (n<100)
{
unitati=n%10, zeci=n/10;
suma = zeci+unitati;
cout << suma;
}
else
{
sute=(n/100)%10;
unitati=n%10;
catul=sute/unitati;
rest=sute%unitati;
suma=catul+rest;
cout << suma;
}
}
return 0;
}