a,b = map(int,input().split())
n = a + b
fac_arr = [1] * (n+1)
r_s_fac_arr = [1] * (n+1)
mod = 998244353 
for i in range(1,n+1):
    fac_arr[i] = (fac_arr[i-1]) * i % mod
    fac_arr[i] %= mod
r_s_fac_arr[n] = pow(fac_arr[n],mod-2,mod)
for i in range(n-1,-1,-1):
    r_s_fac_arr[i] = (r_s_fac_arr[i+1] % mod) * (i+1)
    r_s_fac_arr[i] %= mod
def nckMod(n,k):
    return fac_arr[n]  % mod *  r_s_fac_arr[k] % mod * r_s_fac_arr[n-k] % mod
print(nckMod(a+b-2,a-1))