What is the output of the program for the following input?

int pop (void); /* pop the top of the stack */
void flagError ();

int main ()
{
    int c, m, n, r;
    while ((c = getchar ()) != EOF)
    {
        if (isdigit (c))
            push (c);
        else if ((c == '+') || (c == '*'))
        {
            m = pop ();
            n = pop ();
            r = (c == '+') ? n + m : n*m;
            push (r);
        }
        else if (c != '\n')
            flagError ();
    }
    printf("% c", pop ());
}

What is the output of the program for the following input?
52*33 2 + *