#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001

template <class S,
          S (*op0)(S, S),
          S (*e0)(),
		  S (*op1)(S, S),
          S (*e1)()
          >
struct matrix{
	vector<vector<S>> v;
	int _h,_w;
	
	matrix(vector<vector<S>> X){
		v = X;
		_h = X.size();
		_w = 0;
		if(X.size()>0)_w = X[0].size();
	}
	
	matrix(int h,int w){
		v.resize(h,vector<S>(w,e0()));
		_h = h;
		_w = w;
	}
	
	void add_element(int from,int to,S x){
		v[to][from] = op0(v[to][from],x);
	}
	
	matrix e(){
		assert(_h==_w);
		matrix<S,op0,e0,op1,e1> ret(_h,_w);
		for(int i=0;i<_h;i++){
			for(int j=0;j<_w;j++){
				if(i==j)ret.v[i][j] = e1();
				else ret.v[i][j] = e0();
			}
		}
		return ret;
	}
	
	matrix &operator*=(const matrix &another){
		matrix<S,op0,e0,op1,e1> ret(_h,another._w);
		for(int i=0;i<_h;i++){
			for(int j=0;j<another._w;j++){
				ret.v[i][j] = e0();
				for(int k=0;k<_w;k++){
					ret.v[i][j] = op0(ret.v[i][j],op1(v[i][k],another.v[k][j]));
				}
			}
		}

		v = ret.v;
		return (*this);
	}
	
	matrix operator*(const matrix &another)const{
		return (matrix(*this)*=another);
	}
	
	matrix pow(long long cnt){
		matrix<S,op0,e0,op1,e1> ret = e();
		auto temp = *this;
		while(cnt!=0LL){
			if((cnt&1)==1){
				ret *= temp;
			}
			temp *= temp;
			cnt>>=1;
		}
		return ret;
	}
};

mint op0(mint a,mint b){
	return a+b;
}

mint e0(){
	return 0;
}

mint op1(mint a,mint b){
	return a*b;
}

mint e1(){
	return 1;
}
long long n;
mint get(mint p){
	//cout<<(p*4).val()<<endl;
	matrix<mint,op0,e0,op1,e1> M(2,2);
	rep(i,2){
		rep(j,2){
			if(i==j)M.add_element(i,j,1-p);
			else M.add_element(i,j,p);
		}
	}
	matrix<mint,op0,e0,op1,e1> t(2,1);
	t.v[0][0] = 1;
	M = M.pow(n) * t;
	return M.v[0][0];
}

int main(){
	
	long long h,w,k;
	cin>>h>>w>>n>>k;
	
	deque<pair<long long,long long>> x,y;
	rep(i,min(k,h-k+1)-1){
		if(x.size()==h)break;
		x.emplace_back(i+1,1);
		if(x.size()==h)break;
		x.emplace_back(i+1,1);
	}
	if(x.size()<h)x.emplace_back(min(k,h-k+1),h-x.size());
	
	rep(i,min(k,w-k+1)-1){
		if(y.size()==w)break;
		y.emplace_back(i+1,1);
		if(y.size()==w)break;
		y.emplace_back(i+1,1);
	}
	if(y.size()<w)y.emplace_back(min(k,w-k+1),w-y.size());
	mint ans = 0;
	rep(i,x.size()){
		rep(j,y.size()){
			mint p = x[i].first;
			p *= y[j].first;
			p /= h+1-k;
			p /= w+1-k;
			mint r = 1 - mint(1-p).pow(n);
			r *= x[i].second;
			r *= y[j].second;
			ans += r;
			
		}
	}
	cout<<ans.val()<<endl;
	return 0;
}