#include <iostream>
using namespace std;
int main (){
int a,b;
      cin>>a;
            cin>>b;
int d=0;
       for(int e=a+1;e<b-1;e=e+1){
       	if(e% 400 == 0 || (e % 4 == 0 &&e % 100!=0)){
       			d=d+e;
		   } 
       
       }
       cout<<d;
       return 0;
   }