#include<iostream>
using namespace std;
bool f(int n){
    if((n % 4 == 0 && n % 100 != 0) || n % 400 == 0){
        return true;
    }else{
        return false;
    }
}
int main(){
    int a,b,sum = 0;
    cin>>a>>b;
    for(int i = a - 1;i < b;i++){
        if(f(i)){
            sum += i;
        }
    }
    cout<<sum;
}