program kiem_tra_nguyen_to;
uses crt;
var n,i:integer; bl:boolean;
begin
 clrscr;
 bl:=true;
 write('nhap vao so can kiem tra tinh nguyen to: '); readln(n);
 if n<=1 then bl:=false;
 for i:=2 to trunc(sqrt(n)) then
  if n mod i=0 then bl:=false;
 if bl=true then write('so vua nhap nguyen to.')
 else write('so vua nhap khong nguyen to.');
readln;
end.