var
   n,k,i,j:longint;
   a:array[0..100000]of longint;


procedure Sort(l, r: Integer);
var
  i, j, x, y: integer;
begin
  i := l; j := r; x := a[(l+r) DIV 2];
  repeat
    while a[i] < x do i := i + 1;
    while x < a[j] do j := j - 1;
    if i <= j then
    begin
      y := a[i]; a[i] := a[j]; a[j] := y;
      i := i + 1; j := j - 1;
    end;
  until i > j;
  if l < j then Sort(l, j);
  if i < r then Sort(i, r);
end;


begin
 assign(input,'chess.in');reset(input);
 assign(output,'chess.out');rewrite(output);
 readln(n,k);
 for i:=1 to n do readln(a[i]);
 sort(1,n);
 for i:=1 to n-1 do a[i]:=a[i+1]-a[i] ;
 sort(1,n-1);
 j:=0;
 for i:=1 to k do j:=j+a[i];

 writeln(j);
 close(input);close(output);

end.