View Code of Problem 27

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

long long isSu(int n){
    if (n==1)
        return 0;
    else if (n==2)
        return 1;
    else {
        for (int i = 2; i <= sqrt(n); ++i) {
            if (n%i==0)
                return 0;
        }
    }
    return 1;
}

int main() {
    int a,b;
    while (cin>>a>>b){
        long long sum=0;
        if(a>b){
			int t=a;
			a=b;
			b=t;
		}
        for (int i = a+1; i < b; ++i) {
            if (isSu(i))
                sum+=i;
        }
        cout<<sum<<endl;
    }
    
    return 0;
}