#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first
#define se second
const ll mod=998244353;
const int N=3e5+5;
const int iu=3e5;
ll x,y,z,k;
ll f[N],inf[N];
ll pw(ll x,ll y){
	if(y==0) return 1;
	if(y%2) return x*pw(x,y-1)%mod;
	ll res=pw(x,y/2);
	return res*res%mod;
}
ll C(ll x,ll y){
	return f[x]*inf[x-y]%mod*inf[y]%mod;
}
int main(){
	ios::sync_with_stdio(false);cin.tie(0);
	cin >> x >> y >> z >> k;
	f[0]=1;
	for(int i=1; i<=iu ;i++) f[i]=f[i-1]*i%mod;
	inf[iu]=pw(f[iu],mod-2);
	for(int i=iu; i>=1 ;i--) inf[i-1]=inf[i]*i%mod;
	ll n=x+y+z;
	ll tot=C(x+y+z,x)*C(y+z,y)%mod*f[y]%mod;
	ll cum=0;
	for(int i=1; i<=n-x+1 ;i++){
		ll frog=C(n-i,x-1);
		ll ways=0;
		int st=i-k;
		if(st<=0) ways=f[y+z]*inf[z]%mod;
		else if(st<=y) ways=pw(n-i-x+k+1,st)*f[y+z-st]%mod*inf[z]%mod;
		else ways=pw(n-i-x+k+1,y);
		cum=(cum+frog*ways)%mod;
		//cout << i << ' ' << frog << ' ' << ways << ' ' << n-i-x+k+1 << endl;;
	}
	cum=cum*pw(tot,mod-2)%mod;
	cout << cum << '\n';
}