program kiem_tra_so_nguyen_to;
var
N, i: Integer;
laSoNguyenTo: Boolean;
begin
Write('Nhap vao mot so nguyen duong N: ');
Readln(N);
laSoNguyenTo := True;
if (N < 2) then
laSoNguyenTo := False
else
begin
for i := 2 to N - 1 do
begin
if (N mod i = 0) then
begin
laSoNguyenTo := False;
Break;
end;
end;
end;
if (laSoNguyenTo) then
Writeln(N, ' la so nguyen to')
else
Writeln(N, ' khong la so nguyen to');
Readln;
end.