# include <stdio.h>
/** Auto to programma bazei protous arithmous se ena 
   arxeio. O xristis epilegei mia epilogi apo ena 
   menu. Analoga me tin epilogi eite bazei arithmous
   sto arxeio eite emfanizei to arxeio **/


int menu()
{
	int option;
	printf("1- Store a prime integer \n");
        printf("2- Display the file \n");
	printf("3- Quit\n");
	scanf("%d",&option);
	return option;
}

int isPrime(int x)
{
	int i;
	if(x<=0) return 0;
	for(i=2;i<x/2;i++) 
		if(x%i==0) return 0;
	return 1;
}

int main()
{
	int option,x;
	FILE *fp;
	do
	{
		option=menu();
		if(option==1)
		{
			printf("Please give an integer \n");
			scanf("%d",&x);	
			if(isPrime(x))
			{
				fp=fopen("primes.txt","a");
				fprintf(fp,"%d\n",x);
				fclose(fp);
			}
		}
		else
		if(option==2)
		{
			fp=fopen("primes.txt","r");
			while(fscanf(fp,"%d",&x)>0)
				printf("Prime: %d\n",x);
			fclose(fp);
		}
	}while(option!=3);
	return 0;
}