program cch(input,output);
var
 i,n,k,c,j,maxf,minf,q:longint;
 ans:int64;
 data:array[1..100000] of longint;
 max,min:array[1..1000,1..1000] of longint;
 f:array[0..1000,0..1000] of int64;
begin
 assign(input,'divide.in');
 assign(output,'divide.out');
 reset(input);
 rewrite(output);
 readln(n,k,c);
 for i:=1 to n do read(data[i]);
 for i:=1 to n do
  begin
   maxf:=data[i]; minf:=data[i];
   for j:=i+1 to n do
    begin
     if maxf<data[j] then maxf:=data[j];
     if minf>data[j] then minf:=data[j];
     max[i,j]:=maxf; min[i,j]:=minf;
    end;
  end;
 f[0,0]:=0;
 for i:=1 to n do
  for j:=1 to (i div k) do
   begin
    f[i,j]:=100000000;
    for q:=0 to (j-1) div k do
     if f[i,j]>f[q,j-1]+sqr(max[q+1,i]-min[q+1,i])+c then
      f[i,j]:=f[q,j-1]+sqr(max[q+1,i]-min[q+1,i])+c;
   end;
 ans:=1000000000;
 for i:=1 to n div k do
  if ans>f[n,i] then ans:=f[n,i];
 write(ans);
 close(input);
 close(output);
end.