#include <stdio.h>
#include <math.h>
int main (void){
int x,i,a;
int S1=0,S2=1;
float S3=0;

do {
  printf("Enter x (x>5): \n");
  scanf("%d", &x);
} while (x<=5);
    for (i = 1;i<=x;i++){
      S1=S1+i;
      S2=S2*i;
      S3=S3+1.0/i;
    }
        printf("S1=%d\n",S1);
        printf("S2=%d\n",S2);
        printf("S3=%f\n",S3);

   printf("Reinput x: ");
  scanf("%d", &x);
  	if (x <2){
  		printf("This number is not a prime number\n");
  	return 0;
  	}
  	for (i=2;i<=sqrt(x);i++){
	  if (x%i == 0){{
	  a++;}
	  }
  	}
  	if (a==0){
  		printf("x is a prime number\n");
  		}
  		else printf("x is not a prime number\n");
return 0;
}