text: Binary search to find the number of possible values of the first element
code: while l <= r : NEW_LINE INDENT m = ( l + r ) // 2 NEW_LINE if indices [ x ] [ m ] < i : NEW_LINE INDENT first = m NEW_LINE l = m + 1 NEW_LINE DEDENT else : NEW_LINE INDENT r = m - 1 NEW_LINE DEDENT DEDENT l = 0 NEW_LINE r = len ( indices [ z ] ) - 1 NEW_LINE third = - 1 NEW_LINE