#include<set>

#include<map>

#include<ctime>

#include<queue>

#include<cmath>

#include<cstdio>

#include<vector>

#include<cstring>

#include<cstdlib>

#include<iostream>

#include<algorithm>

#define inf 100000000000000LL

#define pa pair<int,int>

#define ll long long

#define N 2505

#define fp(a,b,c) for(int a=b;a<=c;a++)

#define fd(a,b,c) for(int a=c;a>=b;a--)

using namespace std;

int n,m,K,ans;

int a[N][N],b[N][N],c[N][N],d[N][N],s[N][N];

int main()

{

    scanf("%d%d%d",&n,&m,&K);

    fp(i,,n)fp(j,,m)

    {

        int x;scanf("%d",&x);

        s[i][j]=s[i-][j]+s[i][j-]-s[i-][j-]+x;

    }

    fd(i,K,n)fd(j,K,m)s[i][j]-=s[i-K][j]+s[i][j-K]-s[i-K][j-K];

    fp(i,K,n)fp(j,K,m)a[i][j]=max(s[i][j],max(a[i-][j],a[i][j-]));

    fp(i,K,n)fd(j,K,m)b[i][j]=max(s[i][j],max(b[i-][j],b[i][j+]));

    fd(i,K,n)fp(j,K,m)c[i][j]=max(s[i][j],max(c[i+][j],c[i][j-]));

    fd(i,K,n)fd(j,K,m)d[i][j]=max(s[i][j],max(d[i+][j],d[i][j+]));

    fp(i,K,n-K)fp(j,K,m-K)ans=max(ans,a[i][j]+b[i][j+K]+c[i+K][m]);

    fp(i,K,n-K)fp(j,K+K,m)ans=max(ans,b[i][j]+d[i+K][j]+a[n][j-K]);

    fp(i,K+K,n)fp(j,K,m-K)ans=max(ans,c[i][j]+d[i][j+K]+a[i-K][m]);

    fp(i,K,n-K)fp(j,K,m-K)ans=max(ans,a[i][j]+c[i+K][j]+b[n][j+K]);

    fp(i,K,n)fp(j,K+K,m-K)ans=max(ans,s[i][j]+a[n][j-K]+b[n][j+K]);

    fp(i,K+K,n-K)fp(j,K,m)ans=max(ans,s[i][j]+a[i-K][m]+c[i+K][m]);

    printf("%d\n",ans);

    return ;

}