Program to find area of 4 walls using SUB

DECLARE SUB AREA(L,B,H)
CLS
INPUT"ENTER LENGTH":L
INPUT"ENTER BREADTH";B
INPUT"ENTER HEIGHT";H
CALL AREA(L,B,H)
END

SUB AREA(L,B,H)
A=2*H*(L+B)
PRINT"Area of 4 walls=";A
END SUB