using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Diagnostics;
//using nint=System.Int32;
static class Program{
	const int mod=(int)1e9+7;
	static void Main(){
		Sc sc=new Sc();
		var (a,b,x,y)=sc.Tp4<int>();
		Mint ans=0;
		Cb r=new Cb(a+b);
		var h=new int[4];
		var z=Fu(b+1,4);
		for(int i = 0;i<4;i++) {h[i]=(int)(i<z.Item4?z.Item3:z.Item1);}
		for(int i = 0;i<=a;i++) {
			int d=i-x;
			if(d<0){continue;}
			int e=a-i-d;
			if(((e-y)&1)==1){continue;}
			int g=(e-y)>>1,f=e-g;
			if(g<0||f<0){continue;}
			Mint p=r.C1(h[0]+i-1,i);
			if(d!=0){p*=r.C1(h[2]+d-1,d);}
			if(f!=0){p*=r.C1(h[1]+f-1,f);}
			if(g!=0){p*=r.C1(h[3]+g-1,g);}
			ans+=p;
		}
		Console.WriteLine("{0}",ans);
	}
	static (long,long,long,long) Fu(long n,long p) {return (n/p,p-(n-n/p*p),n/p+1,n-n/p*p);}
}
public class Cb{
	private const int mod=(int)1e9+7;
	public long[] r,f,v;
	public Cb(int n){
		r=new long[n];
		f=new long[n];
		v=new long[n];
		r[0]=r[1]=f[0]=f[1]=v[1]=1;
		for(int i=2;i<n;i++){
			r[i]=r[i-1]*i%mod;
			v[i]=mod-v[mod%i]*(mod/i)%mod;
			f[i]=f[i-1]*v[i]%mod;
		}
	}
	public long C1(long n,long k){return r[n]*(f[k]*f[n-k]%mod)%mod;}
	public long C2(long n,long k){
		long l=1;
		n%=mod;
		for(int i=1;i<=k;i++){l=l*(n-i+1)%mod;l=l*v[i]%mod;}
		return l;
	}
	public long C3(long n,long k){return (r[n]*Mi(r[k]*r[n-k]))%mod;}
	public long P1(long n,long k){return n>=k?r[n]*Mi(r[n-k])%mod:0;}
	public long Mi(long a){
		a=(a+mod)%mod;
		long b=mod,u=1,v=0;
		while(b>0){long t=a/b;a-=t*b;(a,b)=(b,a);u-=t*v;(u,v)=(v,u);}
		u%=mod;
		if(u<0){u+=mod;}
		return u%mod;
	}
}
public struct Mint{
	const int mod=(int)1e9+7;
	private long d;
	public Mint(long d){this.d=d;}
	public static implicit operator Mint(long d){return new Mint(d%mod);}
	public static explicit operator long(Mint d){return d.d;}
	public override string ToString(){return d.ToString();}
	public static Mint operator+(Mint a,long b){a.d=(mod+a.d+b%mod)%mod;return a;}
	public static Mint operator+(Mint a,Mint b){a.d=(a.d+b.d)%mod;return a;}
	public static Mint operator-(Mint a,long b){a.d=(mod+a.d-b%mod)%mod;return a;}
	public static Mint operator-(Mint a,Mint b){a.d=(mod+a.d-b.d)%mod;return a;}
	public static Mint operator*(Mint a,long b){a.d=b%mod*a.d%mod;return a;}
	public static Mint operator*(Mint a,Mint b){a.d=a.d*b.d%mod;return a;}
	public static Mint operator/(Mint a,long b){a.d=a.d*Mi(b)%mod;return a;}
	public static Mint operator/(Mint a,Mint b){a.d=a.d*Mi(b.d)%mod;return a;}
	public static bool operator==(Mint a,long b){return (long)a==b;}
	public static bool operator!=(Mint a,long b){return (long)a!=b;}
	public override bool Equals(object obj){return false;}
	public override int GetHashCode(){return 0;}
	public static long Mi(long a){
		a=(a+mod)%mod;
		long b=mod,u=1,v=0;
		while(b>0){
			long t=a/b;
			a-=t*b;(a,b)=(b,a);
			u-=t*v;(u,v)=(v,u);
		}
		u%=mod;
		if(u<0){u+=mod;}
		return u%mod;
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public int[] Ia3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public long[] La3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
	public (T,T) Tp2<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]));}
	public (T,T,T) Tp3<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]),Ct<T>(s[2]));}
	public (T,T,T,T) Tp4<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]),Ct<T>(s[2]),Ct<T>(s[3]));}
	public (T1,T2) Tp2<T1,T2>(){var s=Console.ReadLine().Split();return (Ct<T1>(s[0]),Ct<T2>(s[1]));}
	public (T1,T1,T2) Tp3<T1,T2>(){var s=Console.ReadLine().Split();return (Ct<T1>(s[0]),Ct<T1>(s[1]),Ct<T2>(s[2]));}
	private T Ct<T>(string s){return (T)Convert.ChangeType(s,typeof(T));}
}