def convolution(F,a):
    """
    return: f(x)*(x-a)
    """
    _N=len(F)
    res=[0]+F[:]
    for i in range(_N)[::-1]:
        res[i]+=F[i]*(-a)
        res[i]%=MOD
    return res

def division(F,a):
    """
    return: f(x)/(x-a)の 商, 余り
    """
    res=[0]*len(F)
    res[-1]=F[-1]
    for i in range(len(F)-1)[::-1]:
        res[i]=(F[i]+a*res[i+1])
        res[i]%=MOD
    return res[1:], res[0]

def evaluation(F,a):
    """
    :return: F(a)
    """
    q,r=division(F,a)
    return r

def differentiate(F):
    """
    O(N)
    """
    res=[0]*(len(F)-1)
    for i in range(len(F)):
        res[i-1]=F[i]*i
    return res

def FindFunction(A,B):
    def gcd_ext(a0,b0):
        a,b=abs(a0),abs(b0)
        sign_a,sing_b=(a0>0)-(a0<0),(b0>0)-(b0<0)
        x0,y0,x,y=0,1,1,0
        while b!=0:
            q=a//b
            a,b=b,a%b
            x0,y0,x,y=x-q*x0,y-q*y0,x0,y0
        return (x*sign_a,y*sing_b)

    def mod_inv(a,MOD):
        """
        gcd(a,MOD)=1 を満たす必要あり
        """
        x,y=gcd_ext(a,MOD)
        return x%MOD

    _N=len(A)
    F=[1]
    for a in A:
        F=convolution(F,a)
    Fs=[]
    for a in A:
        q,r=division(F,a)
        Fs.append(q)
    C=[]
    for i,b in enumerate(B):
        val=evaluation(Fs[i],A[i])
        C.append(b*mod_inv(val,MOD)%MOD)
    res=[0]*(_N)
    for c,F in zip(C,Fs):
        for i,p in enumerate(F):
            if i>=_N:
                continue
            res[i]+=c*p
            res[i]%=MOD
    return res

#######################################################################


from collections import Counter

MOD=998244353

N=int(input())
A=list(map(int, input().split()))
f=[1]
for a in A:
    f=convolution(f,a)
    f=convolution(f,-a)
C=[]
P=Counter(A).items()
for a,cnt in P:
    g=f[:]
    for _ in range(cnt):
        g,_=division(g,a)
    tmp=0
    if cnt!=1:
        for b,_ in P:
            if a==b:continue
            q,r=division(g,b)
            tmp+=pow(evaluation(q,b)*pow((a-b),cnt-1,MOD),MOD-2,MOD)
            tmp%=MOD
    else:
        tmp=pow(evaluation(g,a),MOD-2,MOD)


    C.append(tmp)

res=0
sign=pow(-1,(N-1)%2)
for c in C:
    res+=c*sign
    res%=MOD
print(res*2%MOD)