Problema 9 tema suplimentara

#include <iostream>

using namespace std;

int main()
{
   int S=0,n,cif;
   cout<<"n="<<endl;
   cin>>n;
   while (n)
   {
       cif=n%10;
       S=S+cif;
       if (S>=10)
       S=S%10+S/10;
       n=n/10;
   }
    cout<<S;
    return 0;

}