#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
    int a,b,num=0,t;
    cin>>a>>b;
    if(b>a)
    {
        t=b;
        b=a;
        a=t;
    }
    if(a-b!=0)
    {
        for(int i=1;i<=a-b-1;i++)
    {
        int c=0;
        c=b+i;
        if(c%2==0)
        continue;
        else
        num+=c;
    }
    cout<<num<<endl;
    }
    else
    cout<<"0"<<endl;
    return 0;
}