public class DemoAssignment
{
    public static void main(String[] args)
    {
        short  a = 1;
        int    b = 2;
        float  c = 3e20f;
        double d = 4e20;

        d = a;        // Allowed
        c = b;        // Allowed
        a = d;        // Disallowed
        b = c;        // Disallowed
    }
}