he moved the bracket,
0 = (1-1) + (1-1) + (1-1) ... FIRST LINE yeah this is true
0 = 1 - (1 - 1) - (1 - 1) - (1 - 1) ... SECOND if the amount of numbers in this series hasn't changed (and it can't) it should end with -1, not -(1-1) which is -1 + 1.
You can't really say LS = RS if RS =/= RS
