MOD=998244353
fac=[1,1]
inv=[1,1]
ifac=[1,1]
for i in range(2,10**6):
    fac.append(i*fac[-1]%MOD)
    inv.append(MOD-MOD//i*inv[MOD%i]%MOD)
    ifac.append(ifac[-1]*inv[i]%MOD)

def comb(n,k):
    if n<0 or k<0 or n-k<0:
        return 0
    return fac[n]*ifac[k]%MOD*ifac[n-k]%MOD

N,M,A,B=map(int,input().split())
r=B-A*(N-1)
if r<0:
    exit(print(0))
ans=0
for R in range(r+1):
    ma=A*(N-1)+R+1
    if ma>M:
        continue
    ans+=comb(R+N-2,N-2)*(M-ma+1)%MOD
    ans%=MOD
print(ans*fac[N]%MOD)