View Code of Problem 27

#include<stdio.h>
#include<math.h>
int main(){
	int a, b, flag;
	long long sum;
	while(~scanf("%d%d",&a, &b)){
		int i, j;
		if(a > b){
			a = a + b;
			b = a - b;
			a = a - b;
		}
		sum = 0;
		for(i = a + 1; i < b; i ++){
			if(i == 1 || i == 0){
				sum = 0;
			} else {
				flag = 0;
				for(j = 2; j <= sqrt(i); j ++){
					if(i % j == 0){
						flag = 1;
						break;
					}
				}
				if(flag == 0){
					sum += i;
				}
			}
		}
		printf("%d\n",sum);
	}
	return 0;
}