#include<bits/stdc++.h> using namespace std; //priority_queue<int,vector<int>,greater<int> >t; int main() { long long x,a,b,s=0; cin>>a>>b; x=(a%2==0?a+1:a); for(int i=x;i<=b;i+=2) { if(i%2!=0) { s+=i; } } cout<<s; return 0; }