SIZE=10**6+1; MOD=10**9+7 #998244353 #ここを変更する

inv = [0]*SIZE  # inv[j] = j^{-1} mod MOD
fac = [0]*SIZE  # fac[j] = j! mod MOD
finv = [0]*SIZE # finv[j] = (j!)^{-1} mod MOD
fac[0] = fac[1] = 1
finv[0] = finv[1] = 1
for i in range(2,SIZE):
    fac[i] = fac[i-1]*i%MOD
finv[-1] = pow(fac[-1],MOD-2,MOD)
for i in range(SIZE-1,0,-1):
    finv[i-1] = finv[i]*i%MOD
    inv[i] = finv[i]*fac[i-1]%MOD

def choose(n,r): # nCk mod MOD の計算
    if 0 <= r <= n:
        return (fac[n]*finv[r]%MOD)*finv[n-r]%MOD
    else:
        return 0

def chofuku(box,ball): # nHk mod MOD の計算
    if box == ball == 0: return 1
    return choose(box+ball-1,ball)

n,m,d1,d2 = map(int,input().split())
n -= 1
m -= d1*n+1
d = d2-d1+1
dp = [0]*(m+1)
r = 1
for i in range(n+1):
    if d*i > m: break
    dp[d*i] = choose(n,i)*r
    r *= -1
ans = 0
for i,ai in enumerate(dp):
    ans += chofuku(n+2,m-i)*ai%MOD
print(ans%MOD)