#include <bits/stdc++.h>
using namespace std;
typedef long long LL;

#define int LL

const int mod = 998244353;

int read(void) {
	int s = 0, f = 1;
	char c = getchar();
	while(!isdigit(c)) c = getchar();
	while(isdigit(c)) {
		s = (s << 3) + (s << 1) + (c ^ 48);
		c = getchar(); 
	}
	return s * f;
}

int query(int n) {
	int ans = 0;
	for(int l = 1, r; l <= n; l = r+1) {
		r = min(n / (n / l), n);
		ans += (r % mod - l % mod + 1) % mod * ((n / l) % mod), ans %= mod;
	}
	return (ans % mod + mod) % mod;
}

int l, r;

signed main(void) {
	cin >> l >> r;
	cout << (query(r) - query(l-1)) % mod << endl;
	return 0;
}