#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
using mint = modint998244353;
const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int h, w, n, k; cin >> h >> w >> n >> k;
	vector<mint>cx(k + 1), cy(k + 1);
	if (k * 2 <= h) {
		rep2(i, 1, k)cx[i] = 2;
		cx[k] = h - 2 * (k - 1);
	}
	else {
		rep2(i, 1, h - k + 1)cx[i] = 2;
		cx[h - k + 1] = h - 2 * (h - k);
	}
	if (k * 2 <= w) {
		rep2(i, 1, k)cy[i] = 2;
		cy[k] = w - 2 * (k - 1);
	}
	else {
		rep2(i, 1, w - k + 1)cy[i] = 2;
		cy[w - k + 1] = w - 2 * (w - k);
	}
	mint ans = 0;
	mint m = ((mint)h - k + 1) * (w - k + 1);
	mint inv = m.inv();
	rep2(i, 1, k + 1)rep2(j, 1, k + 1)ans += cx[i] * cy[j] * (mint(1) - ((m - i * j)*inv).pow(n));
	cout << ans.val() << endl;
	return 0;
}