View Code of Problem 27

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main(){
    int a,b,flag,sum;
    while(cin>>a>>b){
        flag=1,sum=0;
        for(int i=a+1;i<b;i++){
            flag=1;
            if(i==1)
                flag=0;
            for(int j=2;j<=sqrt(i);j++){
                if(i%j==0){
                    flag=0;
                    break;
                }
            }
            if(flag==1)
                sum+=i;
        }
        cout<<sum<<endl;
    }
    return 0;
}