View Code of Problem 27

#include<bits/stdc++.h>
using namespace std;

int main() {

	int a,b;
	while(cin>>a>>b){
		long long sum=0;
		for(int i=a+1;i<b;i++){
			int flag=0;
			for(int j=2;j*j<=i;j++){
				if(i%j==0){
					flag=1;
					break;
				}
			}
			if(flag==0){
				sum+=i;
			}
		}
		cout<<sum<<endl;
	}
	return 0;
}