uses crt;
var a,b,tam:integer;
{------------------------------------------------------}
procedure nhap(var n:integer);
begin
write('nhap mot so nguyen bat ky: '); readln(n);
end;
{--------------------------------------------------------}
procedure doicho(var x,y:integer);
begin
writeln('so a truoc khi thay doi la: ',x);
writeln('so b truoc khi thay doi la: ',y);
begin
tam:=x;
x:=y;
y:=tam;
end;
writeln('so a sau khi thay doi la: ',x);
writeln('so b sau khi thay doi la: ',y);
end;
{---------------------------------------------------------}
begin
clrscr;
nhap(a);
nhap(b);
doicho(a,b);
readln;
end.