Program begin_16-

uses crt-

var x1,x2,y1,y2,s,a,b : real-

begin

clrscr-

write(‘x1=’)-readln(x1)-

write(‘y1=’)-readln(y1)-

write(‘x2=’)-readln(x2)-

write(‘y2=’)-readln(y2)-

a:=abs(x2-x1)-

b:=abs(y2-y1)-

s:=a*b-

write(‘s=’,s)-

readln-

end.