#include <iostream>
using namespace std;
#include <atcoder/modint>
using mint = atcoder::modint998244353;

int main() {
    long long N, M;
    cin >> N >> M;
    if (N < M) {
        puts("0");
        return 0;
    }
    mint ret = mint(2).pow(N), tmp = 1;
    for (int t = 0; t < M; ++t) ret -= tmp, tmp = tmp / (t + 1) * (N - t);
    cout << ret.val() << endl;
}