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

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