
ZOJ Problem Set  2319
The most prestigious sports club in one city has exactly N members. Each of its members is strong and beautiful. More precisely, ith member of this club (members being numbered by the time they entered the club) has strength S_{i} and beauty B_{i}. Since this is a very prestigious club, its members are very rich and therefore extraordinary people, so they often extremely hate each other. Strictly speaking, ith member of the club Mr X hates jth member of the club Mr Y if S_{i} <= S_{j} and B_{i} >= B_{j} or if S_{i} >= S_{j} and B_{i} <= B_{j} (if both properties of Mr X are greater then corresponding properties of Mr Y, he doesn��t even notice him, on the other hand, if both of his properties are less, he respects Mr Y very much). To celebrate a new 2005 year, the administration of the club is planning to organize a party. However they are afraid that if two people who hate each other would simultaneouly attend the party, after a drink or two they would start a fight. So no two people who hate each other should be invited. On the other hand, to keep the club prestige at the apropriate level, administration wants to invite as many people as possible. Being the only one among administration who is not afraid of touching a computer, you are to write a program which would find out whom to invite to the party. This problem contains multiple test cases! The first line of a multiple input is an integer N, then a blank line followed by N input blocks. Each input block is in the format indicated in the problem description. There is a blank line between input blocks. The output format consists of N output blocks. There is a blank line between output blocks. Input The first line of the input file contains integer N  the number of members of the club. (2 <= N <= 100 000). Next N lines contain two numbers each  S_{i} and B_{i} respectively (1 <= S_{i}, B_{i} <= 10^{9}). Output On the first line of the output file print the maximum number of the people that can be invited to the party. On the second line output N integers  numbers of members to be invited in arbitrary order. If several solutions exist, output any one. Sample Input
1 Sample Output
2 Author: Andrew Stankevich Source: Andrew Stankevich's Contest #1 