#include <cstdio>

using namespace std;

int main()
{
    short v[301][301];
    char ch[650];
    int n,m,i,j,k,l,r,s,sol=0;
    freopen("teren.in","r",stdin);
    freopen("teren.out","w",stdout);
    scanf("%d %d %d\n",&n,&m,&k);
    for (i=1;i<=n;++i)
        v[i][0]=0;
    for (i=1;i<=n;++i)
    {
        fgets(ch,605,stdin);
        for (j=1;j<=m;++j)
            v[i][j]=v[i][j-1]+ch[j*2-2]-'0';
    }
    for (i=1;i<m;++i)
        for (j=i+1;j<=m;++j)
        {
            l=0;s=0;
            for (r=1;r<=n;++r)
            {
                s+=v[r][j]-v[r][i-1];
                while (l<r&&s>k)
                {
                    ++l;
                    s-=v[l][j]-v[l][i-1];
                }
                if ((r-l)*(j-i+1)>sol)
                    sol=(r-l)*(j-i+1);
            }
        }
    printf("%d\n",sol);
    return 0;
}