#include<stdio.h>
#include<string.h>
#define VMAX 300
int m,n,X,maxim,mat[VMAX][VMAX],apel=1;
unsigned char a[VMAX][VMAX];
char buf[810];
void read()
{   FILE*f=fopen("teren.in","r");
	fscanf(f,"%d %d %d",&n,&m,&X);//f>>n>>m>>X;
	int i,j,var;
	/*for(i=0;i<n;++i)
	for(j=0;j<m;++j)
	{
		fscanf(f,"%d",&var);//f>>var;
		a[i][j]=0;
		if(i>0)a[i][j]+=a[i-1][j];
		a[i][j]+=var;
	}*/
	fgets(buf,10,f);
	int siz,ct;
	for(i=0;i<n;++i)
	{
		fgets(buf,810,f);
		siz=strlen(buf);
		for(j=0,ct=0;j<siz;j+=2,++ct)
		{
			a[i][ct]=0;
			if(i>0)a[i][ct]+=a[i-1][ct];
			a[i][ct]+=buf[j]-48;
		}
	}
	fclose(f);//f.close();
}
int suma(int x1,int y1,int x2,int y2)
{
	int i,s=0;
	for(i=y1;i<=y2;++i)
		if(x1>0)s+=a[x2][i]-a[x1-1][i];
		else s+=a[x2][i];
	return s;
}
void search(int x,int y)
{
	int i=x,j=y,var,s=0,jCreste=1;
	while(i>=x)
	{
		var=(i-x+1)*(j-y+1);
		s=suma(x,y,i,j);
		if(mat[i][j]!=apel)mat[i][j]=apel;
		else s=X+1;
		if(s<=X&&j<m&&i<n)
		{
			if(var>maxim)maxim=var;
			if(mat[i+1][j]!=apel)++i;
			else ++j;
		}
		else
		{
			--i;
			if((i-x+1)*(m-y)<=maxim)i=-1;
			if(mat[i][j]==apel)++j;
		}
		if(i==n)
		{--i;++j;}
		if(j>=m)
		{--j;jCreste=-1;}
	}
}
int solve()
{
	int i,j;
	maxim=0;
	for(i=0;i<n;++i)
	for(j=0;j<m;++j,++apel)
	if((n-i)*(m-j)>maxim)search(i,j);
	
	return maxim;
}
int main()
{
	read();
	FILE*g=fopen("teren.out","w");//ofstream g("teren.out");
	fprintf(g,"%d",solve());//g<<solve();
	fclose(g);//g.close();
	return 0;
}