/**************************************************************

     Problem: 1177

     User: Tunix

     Language: C++

     Result: Accepted

     Time:6088 ms

     Memory:62028 kb

 ****************************************************************/

 //BZOJ 1177

 #include<vector>

 #include<cstdio>

 #include<cstring>

 #include<cstdlib>

 #include<iostream>

 #include<algorithm>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 #define pb push_back

 using namespace std;

 inline int getint(){

     int v=,sign=; char ch=getchar();

     while(ch<''||ch>''){ if (ch=='-') sign=-; ch=getchar();}

     while(ch>=''&&ch<=''){ v=v*+ch-''; ch=getchar();}

     return v*sign;

 }

 const int N=,INF=~0u>>;

 typedef long long LL;

 /******************tamplate*********************/

 int n,m,k;

 typedef int Matrix[N][N];

 Matrix a,b,c,d,s,t;

 int ans;

 int main(){

 #ifndef ONLINE_JUDGE

     freopen("1177.in","r",stdin);

     freopen("1177.out","w",stdout);

 #endif

     n=getint(); m=getint(); k=getint();

     int x;

     F(i,,n) F(j,,m){

         scanf("%d",&x);

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

     }

     F(i,k,n) F(j,k,m) s[i][j]=t[i][j]-t[i-k][j]-t[i][j-k]+t[i-k][j-k];

     F(i,k,n) F(j,k,m) a[i][j]=max(s[i][j],max(a[i-][j],a[i][j-]));

     F(i,k,n) D(j,m,k) b[i][j]=max(s[i][j],max(b[i-][j],b[i][j+]));

     D(i,n,k) F(j,k,m) c[i][j]=max(s[i][j],max(c[i+][j],c[i][j-]));

     D(i,n,k) D(j,m,k) d[i][j]=max(s[i][j],max(d[i+][j],d[i][j+]));

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

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

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

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

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

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

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

     return ;

 }