import sys
input = sys.stdin.readline

N,M=map(int,input().split())
mod=998244353

def Combi2(a,b):# aは大きいが、bは小さいとき
    if b>a:
        return 0
    ANS=1
    for i in range(min(b,a-b)):
        ANS=ANS*(a-i)%mod*pow(min(b,a-b)-i,mod-2,mod)%mod

    return ANS%mod

print(N*Combi2(2*N+M,2*N+1)%mod)