#include <iostream>
using namespace std;
int main()
{
int x,y;
int sum = 0;
cin >> x >> y;
if(x > y) swap(x,y);
for(int i = x + 1;i < y;i ++)
{
if((i + 100) % 2 == 1) sum += i;//这里可以写得清晰一点
}
cout << sum << endl;;
return 0;
}