// Online compiler C++
#include<bits/stdc++.h>
using namespace std ;
#define nl "\n"
#define int long long
using vi = vector<int> ;

void solve() {
    int a , b ;
    cin >> a >> b ;
    
    int res = 0 ;
    for( int i = a ; i <= b ; i++ ) {
        int temp = i ;
        if( temp != 2 && temp % 2 == 0 ) continue ;
        else if( temp == 1 ) continue ;
        
        bool f = true ;
        for( int j = 2 ; j * j <= i ; j++ ) {
            if( i % j == 0 ) {
                f = false ;
                break ;
            }
        }
        
        if( f ) res += pow( i , 3 ) - pow( i , 2 ) + i + 1 ;
    }
    cout << res << nl ;
}
signed main() {
    int t = 1 ;
    // cin >> t ;
    while( t-- ) {
        solve() ;
    }
    return 0 ;
}