perechipare

#include <iostream>
using namespace std;

int main()
{
    int L,R;
    cin>>L>>R;
    int n=(R-L)/2+1;
    if(L%2==1&&R%2==1)
        --n;
    if(L==R)
        if(L%2)
            cout<<0;
        else
            cout<<1;
    else
        cout<<1ULL*n*n;
    return 0;
}