# Colouring Points of the Integer Lattice!

Consider a square in the Cartesian plane whose vertices are $$A(0,0) \ , \ B(10,0) \ , \ C(10,10) \ , \ D(0,10)$$. The grid points of the integer lattice inside or on the boundary of this square are coloured either red or green in such a way that every unit square in the lattice has exactly two red vertices. How many such colorings are possible?

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