Verified answer

var x,y: real;

begin

write('x = ');

readln(x);

if x<=0 then y:=-x

else if x<=2 then y:=x

    else if x<=4 then y:=4-x

         else y:=x-4;

writeln('y = ',y:4:1);

end.

Пример:

x = 3

y =  1.0