//It is made by HolseLee on 18th Jul 2019

//Luogu.org P3935

#include<bits/stdc++.h>

#define mod 998244353

using namespace std;

typedef long long ll;

ll l,r,ans;

int main()

{

    cin>>l>>r; l--;

    for(ll i=,j; i<=r; i=j+) {

        j=r/(r/i);

        ans=(ans+(r/i)*(j-i+)%mod)%mod;

    }

    for(ll i=,j; i<=l; i=j+) {

        j=l/(l/i);

        ans=(ans-(l/i)*(j-i+)%mod+mod)%mod;

    }

    cout<<ans<<'\n';

    return ;

}