M=998244353
n,m=map(int,input().split())
m%=M
a=b=1
for i in range(n):a,b=a*(n+m-i)%M,b*-~i%M
a=[a,0]
r=[a[0]]+[sum(a:=[(a[j-1]*(i-j)%M*(n+m+j)+a[j]*(j+1)%M*(m+j-i+1))%M for j in range(i+1)]+[0])*pow(b:=b*(n+i)%M,-1,M)%M for i in range(1,5001)]
print(sum(r[int(i)]for i in input().split())%M)