n = int(input())
m = int(input())
mod = 998244353

if n < m:
    print(0)
    exit()
    
ans = pow(2,n,mod)-1
nCr = 1
for i in range(m-1):
    nCr *= n-i
    nCr *= pow(1+i,mod-2,mod)
    nCr %= mod
    ans -= nCr
    ans %= mod
print(ans)