Sum of Remainders cf-616E

ll pk;

ll sum(ll n){
    return (((n%mod)*((n+1ll)%mod))%mod * pk)%mod;
}

int main()
{
    booster()
    //read("input.txt");
    ll n,m;
    pk = BigMod<ll>(2,mod-2);
    cin >> n >> m;ll tot = 0;
    ull x = n % mod;
    ull y = m % mod;
    ull ans = (x * y)%mod;
    ll mn = min(n,m);
    m = min(n,m);
    for(ll i = 1;i*i<=n;i++){
        ll le = n / i,ri = n / (i+1);
        le = min(le,m);
        if(ri>=le) continue;
        tot = ((tot + (i * ((sum(le) - sum(ri))%mod + mod )%mod )%mod))%mod;
        tot %= mod;
        mn = ri;
    }
    for(ll i = 1;i<=mn;i++) {
        tot = (tot + ((n/i)%mod * i)%mod)%mod;
        tot %= mod;
    }
    cout << (ans - tot + mod) % mod;

    return 0;
}