MOD = 998244353
N,M = map(int,input().split())

def f1(x):
    return x * (x+1) // 2

def f2(x):
    return x * (x+1) * (2*x+1) // 6

ans = N*(N+1)*M
i = M
while (i):
    v = N // i
    j = N // (v+1)
    ans -= (2*N+2) * v * (f1(i) - f1(j))
    ans += (v+1) * v * (f2(i) - f2(j))
    ans %= MOD
    i = j
print(ans * pow(2,MOD-2,MOD) % MOD)