View Code of Problem 27

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