module mux4to1(a,b,c,d,sel,out);
	input [4:0] a, b, c, d;
	input [1:0] sel;

	output [4:0] out;

	assign out = (sel == 2'b00) ? a : (sel == 2'b01) ? b :
		     (sel == 2'b10) ? c : d;
endmodule