#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    ifstream in;
    ofstream out;
    in.open("heritage.in");
    out.open("heritage.out");
    int m,n,k;
    in>>n>>m>>k;
    int res=-1;
    int A[n][m];
    for(int i=0;i<n;i++)
    {
        for(int t=0;t<m;t++) in>>A[i][t];
    }
    for(int g=1;g<=k;g++)
    {
        if(k%g==0)
        {
            int a=g;
            int b=k/g;
            //cout<<a<<" "<<b<<endl;
            for(int x=0;x<=n-a;x++)
            {
                //cout<<n-a<<" "<<m-b<<endl;
                for(int y=0;y<=m-b;y++)
                {
                    //cout<<x<<" "<<y<<endl;
                    int sum=0;
                    for(int i=x;i<a+x;i++)
                    {

                        for(int t=y;t<b+y;t++)
                        {
                            sum+=A[i][t];
                        }
                    }

                    if(sum>res) res = sum;
                }
            }
        }
    }
    out<<res<<endl;
    return 0;
}