program Teren;
var
   ind : boolean;
   fl : text;
   a : array[1..300,1..300] of byte;
   n, k, j, s, i, m, x, i1, j1, i2, j2, p, n1 : integer;

function findone(i1, j1, i2, j2:integer):integer;
var
   s : integer;
begin
   s := 0;
   for i := i1 to i2 do
      for j := j1 to j2 do
         if a[i,j] = 1 then
            s := s + 1;
   findone := s;
end;
begin
   assign(fl,'teren.in');
   reset(fl);
   readln(fl,m,n,x);
   for i := 1 to m do
      for j := 1 to n do
         read(fl,a[i,j]);
   close(fl);

   s := m*n;
   i1 := 1;
   j1 := 1;
   i2 := m;
   j2 := n;
   while findone(i1, j1, i2, j2) > x do
       j2 := j2 - 1;

   assign(fl,'teren.out');
   rewrite(fl);
   writeln(fl,i2*j2);
   close(fl);

   readln;
end.