n,m,a,b=map(int,input().split())
if (n-1)*a>b:
    print(0);exit()
if n==1:
    print(m);exit()
ans=0;mod=998244353
c=b-(n-1)*a
f=[1]*10**6;g=[1]*10**6
for i in range(1,len(f)):
    f[i]=f[i-1]*i%mod
g[-1]=pow(f[-1],mod-2,mod)
for i in range(len(f)-1,0,-1):
    g[i-1]=g[i]*i%mod
for i in range(1,m+1):
    if i+(n-1)*a>m:
        break
    d=min(c,m-(n-1)*a-i)
    ans+=f[n-1+d]*g[d]%mod*g[n-1]%mod*f[n]%mod
print(ans%mod)