//danhle

var i,n,d:longint;
begin
        read(n);
        for i := 1 to n do
        begin
                if n mod i = 0 then inc(d);
        end;
        if d = 2 then write(n,' la so nguyen to')
        else write(n,' khong phai la so nguyen to');
end.

Program SO_NGUYEN_TO;
Uses crt;
Var i,n: integer;
Begin
Clrscr;
Writeln('KIEM TRA SO NGUYEN TO:');
Writeln('---------------------------');
Write ('Nhap so can kiem tra n = '); readln(n);
If (n=0) or (n=1) then
     Writeln(n,' Khong phai la so nguyen to')
     Else
    Begin
    i:=1;
    Repeat
       i:= i+1;
    Until (n mod i= 0) or (i*i>n);
    If i*i>n then Writeln (n,' la so nguyen to')
    Else Writeln (n,' khong phai la so nguyen to');