#include <fstream>
using namespace std;
long b[302][302],n,m,k;
void citire(){
ifstream fin("teren.in");
fin>>n>>m>>k;
char c;
for (int i=1;i<=n;i++){
long nr=0;
  for (int j=1;j<=m;j++){
      fin>>c;
      nr+=c-'0';
      b[i][j]=b[i-1][j]+nr;}

}
fin.close();
}

long long maxim(){
long long max=0;
for (int i=1;i<=n;i++)
   for (int j=1;j<=m;j++)
      if (b[i][j]<=k)
	if (i*j>max)
	   max=i*j;
return max;
}
int main(){
ofstream fout("teren.out");
citire();
fout<<maxim();
fout<<"\n";
fout.close();
return 0;
}