mod = 1000000007

def mod_build(n) :
    fact = [1]*(n+1)
    inv_fact = [1]*(n+1)
    for i in range(1,n+1):
        fact[i] = fact[i-1]*i %mod
    inv_fact[n] = pow(fact[n],mod-2,mod)
    for i in range(n,0,-1):
        inv_fact[i-1] = inv_fact[i]*i %mod
    return fact, inv_fact
    
def comb(n,k,fact,inv_fact) : 
    if n<0 or k<0 or k>n :
        return 0
    return fact[n]*inv_fact[k]*inv_fact[n-k]%mod

def solve(n,m,d1,d2) :
    m = m-(n-1)*(d1-1)
    if m<0 :
        return 0
    d2=d2-d1+1
    fact, inv_fact = mod_build(m+1)
    ans = 0
    for i in range(0,n):
        ret=comb(m-d2*i,n,fact,inv_fact)*comb(n-1,i,fact,inv_fact)%mod
        if i%2 ==1 : 
            ans+=mod-ret
        else :
            ans+=ret
    return ans%mod

n, m, d1, d2 = map(int, input().split())
print(solve(n, m, d1, d2))