#include<bits/stdc++.h>
#define int long long
#define ll long long
#define pir pair<int,int>
#define fi first
#define se second
#define pb push_back
#define mp make_pair
using namespace std;
inline int re()
{
    int f=1,num=0;
    char c=getchar();
    while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9') num=num*10+c-'0',c=getchar();
    return num*f;
}
int T;
void clear();
const int N=5010,MOD=998244353;
int n,m;
int dp[N][N];
int a[N];
int fac[N],ny[N];
int qpow(int a,int b=MOD-2)
{
    int mul=1;
    while(b)
    {
        if(b&1) mul=mul*a%MOD;
        b>>=1;a=a*a%MOD;
    }
    return mul;
}
int C(int a,int b)
{
    if(a<b) return 0;
    return fac[a]*ny[b]%MOD*ny[a-b]%MOD;
}
void work()
{
    freopen("hopeicansort.in","r",stdin);
    freopen("hopeicansort.out","w",stdout);
    clear();
    fac[0]=1;for(int i=1;i<=5005;i++) fac[i]=fac[i-1]*i%MOD;
    ny[5005]=qpow(fac[5005]);
    ny[0]=1;for(int i=5004;i>=1;i--) ny[i]=ny[i+1]*(i+1)%MOD;
    // cout<<C(2,2)<<' '<<C(3,0)<<endl;
    n=re();m=re();
    int num=0,cnt=0;
    for(int i=1;i<=n;i++)
    {
        a[i]=re();
        if(a[i]==1) num++;
    }
    for(int i=n;n-i+1<=num;i--) if(a[i]==1) cnt++;
    // cout<<num<<' '<<cnt<<endl;
    dp[0][cnt]=1;
    int tmp=qpow(n*(n-1)/2);
    for(int i=1;i<=m;i++)
    {
        for(int j=0;j<=num;j++)
        {
            dp[i][j]=(dp[i-1][j]*(MOD+1-(num-j)*(num-j)%MOD*tmp%MOD)%MOD+
                     (j>=1?dp[i-1][j-1]*(num-j+1)%MOD*(num-j+1)%MOD*tmp%MOD:0))%MOD;
        }
    }
    // cout<<dp[0][2]<<' '<<dp[1][2]<<' '<<dp[2][2]<<endl;
    printf("%lld\n",dp[m][num]%MOD);
}
signed main()
{
    T=1;
    while(T--) work();
    return 0;
}
void clear()
{
    return;
}