C++ :

#pragma GCC optimize ("O2")
#include<bits/stdc++.h>
#include<tr1/unordered_map>
#define pb push_back
#define pii pair<int,int>
#define pvv pair<vector<int>,vector<int>>
#define Fx first
#define Gx second
#define SZ(x) (int)x.size()
#ifdef __linux__
#define getchar getchar_unlocked
#endif
#define mem(a,b) memset(a,b,sizeof(a))
#define  For(i,a,b) for(int i=a,i##E=b;i<=i##E;++i)
#define rFor(i,a,b) for(int i=a,i##E=b;i>=i##E;--i)
typedef long long LL;
using namespace std;
const int N=200010;
const int M=110;
const int inf=0x3f3f3f3f;
const int mod=998244353;
template<typename T>inline bool chkmin(T &a,const T &b){return a>b?a=b,1:0;}
template<typename T>inline bool chkmax(T &a,const T &b){return a<b?a=b,1:0;}
template<typename T>inline void read(T &x)
{
	x=0;int _f(0);char ch=getchar();
	while(!isdigit(ch))_f|=(ch=='-'),ch=getchar();
	while( isdigit(ch))x=x*10+ch-'0',ch=getchar();
	x=_f?-x:x;
}
inline void file()
{
#ifdef ztzshiwo
	freopen("in.txt","r",stdin);
	freopen("out.txt","w",stdout);
#endif
}
int n,m;
int rev[N];
int S[M][M],A[M],B[M],a[N];
int fac[N],ifac[N];
int LGx[N],LFx[N],RGx[N],RFx[N],w[N],iw[N],tot;
inline void Add(int &x,const int&y){x=x+y<mod?x+y:x+y-mod;}
inline int qpow(int a,int b)
{
	int ret=1;
	for(;b;b>>=1,a=1ll*a*a%mod)
		if(b&1)ret=1ll*ret*a%mod;
	return ret;
}
#define Inv(x) qpow(x,mod-2);
inline void init()
{
	fac[0]=ifac[0]=1;
	For(i,1,n)fac[i]=1ll*fac[i-1]*i%mod;
	ifac[n]=Inv(fac[n]);
	rFor(i,n,2)ifac[i-1]=1ll*ifac[i]*i%mod;
	S[0][0]=1;
	For(i,1,m<<1)For(j,0,i)S[i][j]=(1ll*S[i-1][j]*j%mod+(j?S[i-1][j-1]:0))%mod;
	For(i,0,m)A[i]=(1ll*S[m][i]*fac[i]%mod+1ll*S[m][i+1]*fac[i+1]%mod)*ifac[i]%mod;
	int k=m<<1;
	For(i,0,k)B[i]=(1ll*S[k][i]*fac[i]%mod+1ll*S[k][i+1]*fac[i+1]%mod)*ifac[i]%mod;
	tot=1<<16;
	LL ret=qpow(3,mod/tot);
	w[0]=1;
	For(i,1,tot)w[i]=1ll*w[i-1]*ret%mod;
	For(i,0,tot)iw[i]=w[tot-i];
}
inline void Copy(int *x,const vector<int>&S,const int&Base)
{
	For(i,0,SZ(S)-1)x[i]=S[i];
	//memset(x+SZ(S),0,(Base-SZ(S))*sizeof(int));
	fill(x+SZ(S),x+Base,0);
}
inline int init_NTT(const int&n)
{
	int Base=1,len=0;
	for(;Base<=n;Base<<=1)len++;
	For(i,1,Base)rev[i]=(rev[i>>1]>>1)|(i&1)<<(len-1);
	return Base;
}
inline void NTT(int *x,const int&Base,const int&flag)
{
	For(i,0,Base-1)if(i<rev[i])swap(x[i],x[rev[i]]);
	for(int K=2;K<=Base;K<<=1)
	{
		int len=tot/K;
		for(int M=0;M<Base;M+=K)
		{
			int *W=flag?iw:w,l,r,*a=x+M,*b=x+M+(K>>1);
			For(i,0,(K>>1)-1)
			{
				l=*a,r=1ll**b**W%mod;
				Add(*a=l,r),Add(*b=l,mod-r);
				++a,++b,W+=len;
			}
		}
	}
	if(flag){int ret=Inv(Base);For(i,0,Base-1)x[i]=1ll*x[i]*ret%mod;}
}
inline pvv Solve(int l,int r)
{
	if(l==r)
	{
		pvv now;
		now.Fx.resize(m+1),now.Gx.resize((m<<1)+1);
		int ret=1;
		For(i,0,m<<1)
		{
			if(i<=m)now.Fx[i]=1ll*A[i]*ret%mod;
			now.Gx[i]=1ll*B[i]*ret%mod,ret=1ll*ret*a[l]%mod;
		}
		return now;
	}
	int mid=(l+r)>>1;
	pvv L=Solve(l,mid),R=Solve(mid+1,r);
	int Base=init_NTT(max(SZ(L.Fx)+SZ(R.Gx),SZ(L.Gx)+SZ(R.Fx)));
	Copy(LFx,L.Fx,Base),Copy(LGx,L.Gx,Base),Copy(RFx,R.Fx,Base),Copy(RGx,R.Gx,Base);
	NTT(LFx,Base,0),NTT(LGx,Base,0),NTT(RFx,Base,0),NTT(RGx,Base,0);
	For(i,0,Base-1)
	{
		Add(LGx[i]=1ll*LGx[i]*RFx[i]%mod,1ll*LFx[i]*RGx[i]%mod);
		LFx[i]=1ll*LFx[i]*RFx[i]%mod;
	}
	NTT(LFx,Base,1),NTT(LGx,Base,1);
	return make_pair(vector<int>(LFx,LFx+min(n-1,SZ(L.Fx)+SZ(R.Fx))),
					 vector<int>(LGx,LGx+min(n-1,max(SZ(L.Fx)+SZ(R.Gx),SZ(L.Gx)+SZ(R.Fx)))));
}
int main()
{
	file();
	read(n),read(m);
	For(i,1,n)read(a[i]);
	init();
	pvv Ans=Solve(1,n);
	vector<int>G=Ans.Gx;
	int ans=0,ret=1,S=0;
	For(i,1,n)Add(S,a[i]);
	For(i,0,n-2)
	{
		Add(ans,1ll*ret*ifac[i]%mod*G[n-2-i]%mod);
		ret=1ll*ret*S%mod;
	}
	For(i,1,n)ans=1ll*ans*a[i]%mod;
	printf("%lld\n",1ll*ans*fac[n-2]%mod);
	//cerr<<(double)clock()/CLOCKS_PER_SEC<<endl;
	return 0;
}