#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
#include <bits/stdc++.h>
#define rep(i,n) for(int i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
using namespace std;
#define inf 998244353
long long f[1100000];
int n,m;
long long mypow(long long n,long long k)
{
    long long ret=1;
    while (k)
    {
        if (k&1)ret=ret*n%inf;
        n=n*n%inf;
        k>>=1;
    }
    return ret;
}
int main()
{
    cin>>n>>m;
    long long ans=0;
    rep(i,(n-1)/2)
    {
        long long t=mypow(m,i)*(1-f[i/2]+inf)%inf;
        ans=(ans+t*mypow(m,n-2*i)%inf)%inf;
        f[i]=(f[i-1]+t*mypow(m,inf-2*i-1)%inf)%inf;
    }
    cout<<ans<<endl;
    return 0;
}