Program BTT;
Uses crt;
Var n: longint;

Function ngto(a: longint): boolean;
Var i: longint;
Begin
        If a<2 then exit(false);
        For i:=2 to trunc(sqrt(a)) do
                If a mod i = 0 then exit(false);
                                    exit(true);
End;

Begin
        Clrscr;
        Write('Nhap n: '); Readln(n);
        If ngto(n) then Write(n,' la so nguyen to')
        Else Write(n,' khong phai la so nguyen to');
        Readln
End.

var n:longint;

function checkprime(x:longint):boolean;
var c:longint;
begin

        if x<2 then exit(false);
        for c:=2 to trunc(sqrt(x)) do if x mod c = 0 then exit(false) else exit(true);
end;

begin

write('Nhap n: '); readln(n);

if checkprime(n) then write('Day la so nguyen to') else write('Day khong phai la so nguyen to');

readln;

end.