Program Ngto;
Uses crt;
Var a,i,d: longint;
Begin
Clrscr;
Write('Nhap so nguyen duong: '); Readln(a);
If a<2 then Write(a,' khong phai so nguyen to')
ELse
d:=0;
For i:=2 to a div 2 do
If a mod i = 0 then d:=d+1;
If d=0 then Write(a,' la so nguyen to')
Else Write(a,' khong phai so nguyen to');
Readln
End.