#include<cstdio>

#include<algorithm>

#define M 200001

#define mod 100000007

#define ll long long

using namespace std;

ll inv(ll x)

{

    if(x==) return ;

    return inv(mod%x)*(mod-mod/x)%mod;

}

ll C(ll a,ll b)

{

    ll u=,v=,i,t;

    t=max(b,a-b);

    for(i=;i<t;i++){

        u=u*(a-i)%mod;

        v=v*(i+)%mod;

    }

    return u*inv(v)%mod;

}

int main()

{

    ll m,n,q,p;

    while(scanf("%lld%lld%lld%lld",&m,&n,&p,&q)!=EOF){

        ll ans=C(m+n,m)*C(m+q-p,q)%mod-C(m+q,m)*C(m+n-p,n)%mod;

        if(ans<) ans=(ans+mod)%mod;

        printf("%lld\n",ans);

    }

    return ;

}