#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001



int main(){
	
	mint ans = 0;
	long long n,m;
	cin>>n>>m;
	mint cur = 1;
	for(long long i=0;i<m;i++){
		ans += cur;
		cur *= n-i;
		cur /= i+1;
		
	}
	ans = mint(2).pow(n) - ans;
	cout<<ans.val()<<endl;

	return 0;
}