#include<stdio.h>


int find(int n){
	int i, c = 0;
	for(i = n;i > 0;i--){
		if(n % i == 0){
			c++;
		}
	}
	if(c == 2){
		printf("So nguyen to!\n");
	}else{
		printf("Khong phai so nguyen to!\n");
	}
	return 0;
}

int main(){
	do{
		int m;
		printf("Nhap n: ");
		scanf("%d", &m);
		if(m == 0){
			printf("\nthanks for using this shit!");
			break;
		find(m);
		}
	} while(1);
	
	return 0;
}