uses crt;
var a,b,c,d,max: integer;
begin
clrscr;
write ('nhap a: '); readln (a);
write ('nhap b: '); readln (b);
write ('nhap c: '); readln (c);
write ('nhap d: '); readln (d);
max:=a;
if max<b then max:=b;
if max<c then max:=c;
if max<d then max:=d;
write('Gia tri lon nhat la: ',max);
readln;
end.