program solution;

{$APPTYPE CONSOLE}
{MODE DELPHI}
{$MAXSTACKSIZE 1000000000}
{O-,R+,Q+}
{$O+,R-,Q-}

uses
  SysUtils,
  Math;

const
  inf = round(1e9);

var
  n, m, k, ans, i, j : integer;
  a, sum, d, dd : array[0..30001] of integer;

begin
  //assign(input, 'input.txt'); reset(input);
  //assign(output, 'output.txt'); rewrite(output);
  read(n, m, k);
  for i := 1 to n do
    read(a[i]);
  for i := 1 to n do
    sum[i] := sum[i - 1] + a[i];
  ans := -inf;
  for i := 1 to m do begin
    for j := 0 to n do
      dd[j] := -inf;
    for j := 1 to n do begin
      dd[j] := max(dd[j], dd[j - 1]);
      dd[j] := max(dd[j], d[max(j - k, 0)] + sum[j] - sum[max(j - k, 0)]);
    end;
    for j := 0 to n do
      d[j] := dd[j];
    ans := max(ans, d[n]);
  end;
  writeln(ans);
end.