calculating min difference from last index of lists
min_diff = Math . abs ( Math . max ( A [ i ] , Math . max ( B [ j ] , C [ k ] ) ) - Math . min ( A [ i ] , Math . min ( B [ j ] , C [ k ] ) ) ) ; while ( i != - 1 && j != - 1 && k != - 1 ) { current_diff = Math . abs ( Math . max ( A [ i ] , Math . max ( B [ j ] , C [ k ] ) ) - Math . min ( A [ i ] , Math . min ( B [ j ] , C [ k ] ) ) ) ;