obtinerea inversului unui numar (recursiv)

#include <iostream>

using namespace std;
long long numar(int n)
{
    int cif;
    cout<<"cifra"; cin>>cif;
    if(cif<0 || cif>9)
        return n;
    else
        return numar(n*10+cif);
}
int main()
{
    int nr;
    nr=numar(0);
    cout<<"numarul= "<<nr;
    return 0;
}