#include<cstdio>

#include<cstring>

#include<cctype>

#include<cmath>

#include<algorithm>

#define ll long long

using namespace std;

int read(){

    char c;int s=,t=;

    while(!isdigit(c=getchar()))if(c=='-')t=-;

    do{s=s*+c-'';}while(isdigit(c=getchar()));

    return s*t;

}

int min(int a,int b){return a<b?a:b;}

int max(int a,int b){return a<b?b:a;}

int abs(int x){return x>?x:-x;}

void mins(int &a,int b){if(a>b)a=b;}

void maxs(int &a,int b){if(a<b)a=b;}

//void insert(int u,int v){tot++;e[tot].v=v;e[tot].from=first[u];first[u]=tot;}

/*------------------------------------------------------------*/

const int inf=0x3f3f3f3f,maxn=;

int n,m,sum[maxn][maxn],lx,rx,ly,ry,A,B;

bool calc(int lx,int ly,int rx,int ry,int num){return (sum[rx][ry]-sum[rx][ly-]-sum[lx-][ry]+sum[lx-][ly-])>=num;}

bool pd(int num){

    bool yes=;ly=ry=;

    for(int j=;j<=B;j++){

        while(ry+<=m&&!calc(lx,ly,rx,ry,num))ry++;

        if(!calc(lx,ly,rx,ry,num)){yes=;break;}

        ly=++ry;

    }

    return yes;

}

bool check(int num){

    bool ok=;

    lx=,rx=;

    for(int i=;i<=A;i++){

        while(rx+<=n&&!pd(num))rx++;

        if(!pd(num)){ok=;break;}

        lx=++rx;

    }

    return ok;

}

int main(){

    n=read();m=read();A=read();B=read();

    for(int i=;i<=n;i++){

        for(int j=;j<=m;j++)sum[i][j]=sum[i][j-]+read();

        for(int j=;j<=m;j++)sum[i][j]+=sum[i-][j];

    }

    int l=,r=sum[n][m],mid;

    while(l<r){

        mid=(l+r)>>;

        if(check(mid))l=mid+;else r=mid;

    }

    printf("%d",l-);

    return ;

}