#include<bits/stdc++.h>
#include<set>
using namespace std;
int allsum,ksum;
set<pair<int,int> > S;
const int MAXN = 305;
bool del[MAXN];
int a[MAXN][MAXN],sum[MAXN][MAXN];
int n,m,k,s;
#define mk make_pair
inline bool check()
{
	if (S.size() < k) return true;
	if (allsum - ksum <= s) return true;
	return false; 
}
void init(int n,int m)
{
	for (int i=1;i<=n;i++)
	{
		sum[i][0] = 0;
		for (int j=1;j<=m;j++) sum[i][j] = sum[i][j-1] + (a[i][j] == 0 ? 1:0);
	}
}
int main()
{
	while (1)
	{
		scanf("%d%d%d%d",&n,&m,&k,&s);
		//cout<<n<<' '<<m<<' '<<k<<' '<<s<<endl;
		if (n==m && m==k && k==s && n==0) break;
		for (int i=1;i<=n;i++)
		{
			for (int j=1;j<=m;j++)
			{
				scanf("%d",&a[i][j]);
			}
		}
		init(n,m);
		//cout<<"!!!"<<sum[2][5] - sum[2][2]<<endl;
		int ans = 0;
		for (int l=1;l<=m;l++)
			for (int r=l;r<=m;r++)
			{
				int i=0,j=0;
				for (int kk=0;kk<n;kk++) del[kk] = false;
				del[i] = true;
				S.clear();
				allsum = 0;
				ksum = 0;
				while (i<n)
				{
					//cout<<i<<endl;
					if (i!=0)allsum -= sum[i][r] - sum[i][l-1];
					if (del[i] == false) {
						auto p = S.find(mk(sum[i][r] - sum[i][l-1],i));
						ksum -= sum[i][r] - sum[i][l-1];
						S.erase(p);
					}
					i++;
					if (check()) ans = max(ans,(r-l+1)*(j-i+1));
					while (j<n)
					{
						if (!check()) break;	
						//cout<<j<<endl;
						int tmp = sum[j+1][r] - sum[j+1][l-1];
						j++;
						if (S.size() < k) {
							S.insert(mk(tmp,j));
							allsum += tmp;
							ksum += tmp;
						}
						else if ((*S.begin()).first <= tmp) {
							S.insert(mk(tmp,j));
							allsum += tmp;
							ksum += tmp;
							auto x = *S.begin();
							ksum -= x.first;
							//allsum -=x.first;
							del[x.second] = true;
							S.erase(S.begin());
						}
						else {
							allsum += tmp;
							del[j] = true;
						}
						//if (l==3 &&r==5) cout<<i<<' '<<j<<' '<<l<<' '<<r<<' '<<allsum<<' '<<ksum<<endl;
						if (!check()) break;
						else if ((r-l+1)*(j-i+1) >= ans) {
							ans = max(ans,(r-l+1)*(j-i+1));
							//cout<<i<<' '<<j<<' '<<l<<' '<<r<<' '<<allsum<<' '<<ksum<<endl;
						}
					}
				}
			}
		printf("%d\n",ans);
	}
}