In a country called Uncle Sam Land (USL), the labor demand curve is given by:

W = K - 4L

Where W is the wage rate, K is a variable determined by accumulated capital stock in the country, and L is the labor force in the country.

Currently, K = 500 is supplied by the capitalists.

The country has built a strong impenetrable border wall to prevent outsiders from moving in. The labor force is thus currently fixed at 100 (L = 100). All workers work no matter what the wage is.

What is the national income (all wages plus all income of the capitalists) in this country?