# https://drken1215.hatenablog.com/entry/2019/03/18/013100

import sys
input = sys.stdin.readline

mod=10**9+7

FACT=[1]
for i in range(1,2*10**6+1):
    FACT.append(FACT[-1]*i%mod)

FACT_INV=[pow(FACT[-1],mod-2,mod)]
for i in range(2*10**6,0,-1):
    FACT_INV.append(FACT_INV[-1]*i%mod)

FACT_INV.reverse()

def Combi(a,b):
    if 0<=b<=a:
        return FACT[a]*FACT_INV[b]%mod*FACT_INV[a-b]%mod
    else:
        return 0

N,M,D1,D2=map(int,input().split())
M-=D1*(N-1)
d=D2-D1
ANS=0

for i in range(N+1):
    m=M-(d+1)*i
    #print(m)
    if i%2==0:
        ANS+=Combi(N-1,i)*Combi(m+N-1,m-1)
    else:
        ANS-=Combi(N-1,i)*Combi(m+N-1,m-1)

    #print(ANS)

print(ANS%mod)