#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------


const int mo=998244353;
ll modpow(ll a, ll n = mo-2) {
	ll r=1; a%=mo;
	while(n) r=r*((n%2)?a:1)%mo,a=a*a%mo,n>>=1;
	return r;
}


ll comb(ll N_, ll C_) {
	const int NUM_=2400001;
	static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1];
	if (fact[0]==0) {
		inv[1]=fact[0]=factr[0]=1;
		for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo;
		for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo;
	}
	if(C_<0 || C_>N_) return 0;
	return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo;
}

int H,W,N,K;


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	
	cin>>H>>W>>N>>K;
	
	vector<ll> Hs(K+1),Ws(K+1);
	
	int numH=0,Hma=0;;
	int numW=0,Wma=0;;
	if(2*K<=H) {
		for(i=1;i<K;i++) Hs[i]=2;
		Hs[K]=H-2*K+2;
	}
	else {
		for(i=1;i<H-K+1;i++) Hs[i]=2;
		Hs[H-K+1]=2*K-H;
	}
	if(2*K<=W) {
		for(i=1;i<K;i++) Ws[i]=2;
		Ws[K]=W-2*K+2;
	}
	else {
		for(i=1;i<W-K+1;i++) Ws[i]=2;
		Ws[W-K+1]=2*K-W;
	}
	
	ll ret=0;
	ll L=1LL*(H-K+1)*(W-K+1)%mo;
	ll rL=modpow(L);
	
	for(x=1;x<=K;x++) for(y=1;y<=K;y++) {
		ret+=Hs[x]*Ws[y]%mo*(1-modpow((L-x*y)*rL,N))%mo;
	}
	
	ret=(ret%mo+mo)%mo;
	cout<<ret<<endl;
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}