text: Remove the index at present after K indices from the current index
code: remIdx = i - k NEW_LINE if ( remIdx >= 0 ) : NEW_LINE INDENT if ( ( pref [ remIdx ] - remIdx % k + k ) % k in cnt ) : NEW_LINE INDENT cnt [ ( pref [ remIdx ] - remIdx % k + k ) % k ] -= 1 NEW_LINE DEDENT else : NEW_LINE INDENT cnt [ ( pref [ remIdx ] - remIdx % k + k ) % k ] = - 1 NEW_LINE DEDENT DEDENT