Не могу понять в чем ошибка!

program zadacha3_5;
uses CRT;
var xa,ya,xb,yb:real;
begin
clrscr;
textcolor(5);
writeln('vvedite xa,ya,xb,yb');
read(xa,ya,xb,yb);
if(xa>-1)and(xa<0)and(ya<-1)and(ya<0) then writeln('A v oblasti A')
else if (xa>-3)and(ya>-3)or(xa<3)and(ya<3) then writeln ('A v oblasti B')
else if(xa<3)and(ya<3) then writeln ('A v oblasti C')
else writeln ('A v oblasti D');
if (xb>-1) and(xb<1)and(yb>-1)and(yb<1) then writeln('B v oblasti A')
else if (xb>-3)and(yb>-3)and(yb<3) or(xb<3)and(yb<3) then writeln ('B v oblasti B')
else if (xb<3) and(yb<3) then writeln ('B v oblasti C')
else writeln ('B v oblasti D');
if(xa=xb) then writeln('otrezok vertikakniy')
else if (ya=yb) then writeln('otrezok gorizontalniy')
else if (xa<xb) and (ya<yb)or(xa>xb)and(ya>yb) then writeln ('naklonen vverh')
else if (xa<xb)and (ya>yb)or (xa>xb)and (ya<yb) then writeln ('naklonen vniz')
end.