#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> int UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(b<a){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=false){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> T square(T a){return a * a;}



void solve();
// POP'N ROLL MUSIC / TOMOO
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int N, M, C, X;
    cin >> N >> M >> C >> X;
    vector A(N, vector<int>(M));
    rep(i, 0, N) rep(j, 0, M) cin >> A[i][j];
    ll L = -INF, R = INF;
    while (R - L > 1){
        ll mid = (L + R) / 2;
        vector dp(N + 1, vector<int>(M, -INF));
        rep(i, 0, N){
            int a = -INF, b = -INF;
            int best = -1;
            rep(j, 0, M){
                if (chmax(b, dp[i][j])){
                    if (a < b) swap(a, b), best = j;
                }
            }
            if (i == 0) a = 0;
            rep(j, 0, M){
                if (A[i][j] >= mid){
                    if (best == j) chmax(dp[i + 1][j], b);
                    else chmax(dp[i + 1][j], a);
                }
                rep(k, 0, 3){
                    if (i + k == N) break;
                    if (A[i + k][j] - C < mid) break;
                    if (k == 0) continue;
                    if (best == j) chmax(dp[i + 1 + k][j], b + k + 1);
                    else chmax(dp[i + 1 + k][j], a + k + 1);
                }
            }
        }
        if (vec_max(dp[N]) >= X) L = mid;
        else R = mid;
    }
    cout << L << "\n";
}
/*
 * 同じのが連続するのは、2 or 3 だと思っていい
 *
 */