Where is wrong?

This is MY SOLVe!!!

program MEGA;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var i,n,k:integer;
    a:array[1..100] of int64;
    m:int64;
begin
  read(n,k);
  if n=2 then
    begin
    writeln((k-1)*k);
    halt(0);
    end;
  if n=3 then
    begin
    writeln((k-1)*k*k-k+1);
    halt(0);
    end;
  a[3]:=k-1;
  m:=k-1;
  for i:=4 to n do
    begin
    m:=m*(k-1);
    a[i]:=a[i-1]+(i-2)*m;
    end;
  m:=k-1;
  for i:=1 to n-1 do
         m:=m*k;
  writeln(m-a[n]);
end.