View Code of Problem 27

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int judge(int num){
	int flag = 1;
	for(int i=2; i<=sqrt(num*1.0); i++){
		if(num%i==0){
			flag = 0;
			break;
		}	
	}
	if(flag ==1)
		return 1;
	else
		return 0;
}



int main(){
	int a,b;
	while((scanf("%d %d",&a,&b)!=EOF)){
		unsigned long long count = 0;
		for(int i=a+1; i<b; i++){
			if(i==1 || i==2)
				count += i;
			else{
				int result = judge(i);
				if(result==1)
					count += i;
			}
		
		}
		printf("%lld\n",count);
	
	}

	return 0;
}