#include <bits/stdc++.h>
#define lim_n 301
#define lim_m 301
using namespace std;
#define INPUT_FILE "teren.in"
#define OUTPUT_FILE "teren.out"
bool a;
int n,m,x,i,j,k,w,maxx=0;
int v[lim_n][lim_m];
int main()
{
    ios_base::sync_with_stdio(false);
    ifstream in(INPUT_FILE);
    in.tie(0);
    in>>n>>m>>x;
    for(i=1;i<=n;++i)
        for(j=1;j<=m;++j)
        {
            in>>a;
            if(a==1)
            {
                for(k=i;k<=n;++k)
                    for(w=j;w<=m;++w)
                    v[k][w]+=a;
            }
        }
    in.close();
    for(i=1;i<=n-1;++i)
        for(j=1;j<=m-1;++j)
            for(k=i+1;k<=n;++k)
                for(w=j+1;w<=m;++w)
                    if(v[k][w]-v[k][j-1]-v[i-1][w]+v[i-1][j-1]<=x)
                        maxx=max(maxx,k*w-k*(j-1)-(i-1)*w+(i-1)*(j-1));
    ofstream out(OUTPUT_FILE);
    out.tie(0);
    out<<maxx;
    out.close();
    return 0;
}