Area of 4wall using function

DECLARE FUNCTION AREA (L,B,H)
CLS
INPUT"ENTER LENGTH";L
INPUT"ENTER BREADTH";B
INPUT"ENRER HEIGHT";H
PRINT"AREA OF 4WALL";AREA(L,B,H)
END

FUNCTION AREA(L,B,H)
A=2*H*(L+B)
AREA=A
END FUNCTION