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

const int mod = 998244353;

int main() {
    int n, k;
    cin >> n >> k;
    
    if (k > n-k) k = n-k;
    
    vector<mint> inv(k+1);
    inv[1] = 1;
    for (int i = 2; i <= k; ++i) {
        inv[i] = (mod-mod/i)*inv[mod%i];
    }
    
    mint ans = 1;
    rep(i, k) ans *= n-i;
    rep(i, k) ans *= inv[i+1];
    
    cout << ans.val() << '\n';
    
    return 0;
}