#include <stdio.h>

int main() {

          int n, i, ngt=1;

          do {printf("Nhap n: ");

                   scanf("%d", &n); } while(n<=0);   for(i=2; i<=sqrt(n); i++) {

                   if(n%i==0)

                             ngt = 0;}  if(ngt==0)

                   printf("\nSo %d khong phai la so nguyen to", n);

          else

                   printf("\nSo %d la so nguyen to", n);}

uses crt;
var n,i:longint;
begin
   clrscr;
   write('Nhap n: '); readln(n);
   i:=2;
   if n<2 then writeln(n,' khong phai la so nguyen to')
   while n mod i<>0 do inc(i);
   if i=n then writeln(n,' la so nguyen to')
   else writeln(n,' khong phai la so nguyen to');
   readln
end.