C program to find Sum of Prime Numbers between 1 to n given by range

#include<stdio.h>
int main()
{
	int start, end, temp, i, j, flag, sum=0;
	printf("Enter Start number: ");
	scanf("%d",&start);
	printf("Enter End number: ");
	scanf("%d",&end);

	if(start == 1)
	{
		temp = start + 1;	//temp for store value by 1 because any prime number is 1 and it self
	}

	/* Find all prime numbers between 1 to enter by user number */
	for(i=temp;i<=end;i++)
	{
		flag = 1;	//initialize flag 1

		//check current number i is a prime or not
		for(j=2;j

Output

Enter Start number: 12                                                                                                                        
Enter End number: 22                                                                                                                          
Sum of all Prime Numbers between 12 to 22 = 78