#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;}
//-------------------------------------------------------

int N,M,C,X;
ll A[2020][202];

int from[202][2];
int to[202][2];

int ok(ll v) {
	int x,y,i;
	FOR(x,M) {
		from[x][0]=from[x][1]=-202020;
		if(A[0][x]>=v) from[x][0]=0;
	}
	for(y=1;y<N;y++) {
		vector<pair<int,int>> V;
		FOR(x,M) {
			to[x][0]=-202020;
			to[x][1]=-202020;
			if(A[y][x]-C>=v) {
				if(A[y-1][x]-C>=v) to[x][1]=max(to[x][1],from[x][0]+2);
				to[x][1]=max(to[x][1],from[x][1]+1);
			}
			V.push_back({max(from[x][0],from[x][1]),x});
		}
		sort(ALL(V));
		reverse(ALL(V));
		FOR(x,M) if(A[y][x]>=v) {
			if(V[0].second!=x) to[x][0]=max(to[x][0],V[0].first);
			else if(M>=2) to[x][0]=max(to[x][0],V[1].first);
		}
		
		swap(from,to);
	}
	FOR(x,M) if(from[x][0]>=X||from[x][1]>=X) return 1;
	return 0;
	
	
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>M>>C>>X;
	FOR(y,N) FOR(x,M) cin>>A[y][x];
	
	ll ret=-1LL<<30;
	for(i=30;i>=0;i--) if(ok(ret+(1<<i))) ret+=1<<i;
	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;
}