?- area.
			Radius |: 1.
			Area is 3.14
			Circumference is 6.28
			yes	
		area:- write('Radius '),read(R),
		        write('Area is '),A is 3.14*R*R,write(A),nl,
		        write('Circumference is '),C is 2*3.14*R,write(C),nl.
			?- start.
			Radius= |: 1.
			Circumference is 6.28
			Area is 3.14
		start:- radius(R),
			circ(R,C),write('Circumference is '),write(C),nl,
			area(R,A),write('Area is '),write(A).
		
                radius(R):- write('Radius= '),read(R).
		
		circ(R,C):- C is 2*3.14*R.
				
		area(R,A):- A is 3.14*R*R.