program hoan_vi;
var x,y:integer;{so nguyen}
function swap(x,y:integer):integer;
var temp:integer;
begin
   temp:=x;
   x:=y;
   y:=temp;
   writeln('trong ham: x= ',x,' y= ',y);
end;
begin
    write('nhap x: ');readln(x);
    write('nhap y: '); readln(y);
    swap(x,y);
    write('ngoai ham: x= ',x,' y= ',y);
    readln;
end.