uses crt;

const
  MAX = 10010;

var
  a: array [1..MAX] of integer;
  n, k, i, j: integer;
  l, r, m, cow : integer;

procedure check;
var
  i: integer;
begin
  for i := 2 to n do
    if a[i] - a[j] >= m then begin
      j := i;
      inc(cow);
    end;
    if cow >= k then
       l := m + 1
    else
        r := m;
end;

begin
  readln(n, k);
  for i := 1 to n do
    read(a[i]);
  l := 0;
  r := a[n] - a[1];;
  while r - l <> 0 do begin
    j := 1;
    cow := 1;
    m := (l + r) div 2;
    //writeln();
    check;
  end;
  writeln(l - 1);
end.