#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int maxn=200000;
const ll mod=998244353;
ll qmksm(ll a,ll b){
    ll res=1;
    while(b){
        if(b&1) res=res*a%mod;
        a=a*a%mod;
        b>>=1;
    }
    return res;
}
ll ny(ll n){
    return qmksm(n,mod-2);
}
int main(){
    ll n,k,i,j,ans,zc,zc1,cur1,cur2;
    scanf("%lld %lld",&n,&k);
    if(k<0 or k>n){
        printf("0\n");
        return 0;
    }
    if(k==0 or k==n){
        printf("1\n");
        return 0;
    }
    if(k>n/2)
        k=n-k;
    cur1=1,cur2=1;
    for(i=1;i<=k;i++){
        cur1=cur1*((n-i+1)%mod)%mod;
        cur2=cur2*i%mod;
    }
    ans=cur1*ny(cur2)%mod;
    printf("%lld\n",ans);
    return 0;
}