program Teren;
label
   001;
const
   ii_0 : array[1..8] of integer = (1, 1, 1, 0, 0, -1, -1, -1);
   jj_0 : array[1..8] of integer = (1, -1, 0, 1, -1, 0, -1, 1);
var
   ind : boolean;
   fl : text;
   a : array[1..300,1..300] of byte;
   b : array[1..300,1..300] of integer;
   pi, pj : array[1..10000] of integer;
   n, k, j, s, i, m, pas, cant, x, s_aux, p, n1, v_pas : integer;

procedure Init;
var
   i, j :integer;
begin
   for i := 1 to m do
      for j := 1 to n do
          b[i,j] := a[i,j];
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);

   n1 := 0;
   for i := 1 to m do
      for j := 1 to n do
        if a[i,j] = 1 then
           begin
              n1 := n1 + 1;
              pi[n1] := i;
              pj[n1] := j;
           end;

   s := 0;
   s_aux := 0;
   for k := 1 to n1 do
      begin
         cant := 0;
         b[pi[k],pj[k]] := 2;
         pas := 2;
         while cant < x do
            begin
               for i := 1 to m do
                  for j := 1 to n do
                     if b[i,j] = pas then
                        begin
                           for p := 1 to 8 do
                             if (b[i+ii_0[p],j+jj_0[p]] = 1) and (i+ii_0[p] <> pi[k]) and (j+jj_0[p]<> pj[k]) then
                                begin
                                   cant := cant + 1;
                                   if cant = x then
                                      v_pas := pas;
                                end;
                           if cant > x then
                              goto 001;
                           for p := 1 to 8 do
                              if b[i+ii_0[p],j+jj_0[p]] = 0 then
                              b[i+ii_0[p],j+jj_0[p]] := pas +1;
                        end;
                pas := pas + 1;
            end;
001: ;
      s_aux := 0;
      for i := 1 to m do
         for j := 1 to n do
            if (b[i,j] <= v_pas) and (b[i,j] <> 0) and (b[i,j] <> 1) then
               s_aux := s_aux + 1;
      if s_aux > s then
         s := s_aux;
      Init;
      end;

   assign(fl,'teren.out');
   rewrite(fl);
   writeln(fl,s);
   close(fl);
end.