Summer again! Flynn is ready for another tour around. Since the tour would take three or more days, it is important to find a hotel that meets for a reasonable price and gets as near as possible!

But there are so many of them! Flynn gets tired to look for any. It’s your time now! Given the for a hotel hi, where pi stands for the price and di is the distance from the destination of this tour, you are going to find those hotels, that either with a lower price or lower distance. Consider hotel h1, if there is a hotel hi, with either lower price or distance, we would discard h1. To be more specific, you are going to find those hotels, where no other has a lower price or distance than it. And the comparison is strict.

### 输入格式

There are some cases. Process to the end of file

Each case begin with N (1 <= N <= 10000), the number of the hotel

The next N line gives the (pi, di) for the i-th hotel.

The number will be a positive and less than 10000.

### 输出格式

First, output the number of the hotel you find, and from the next line, print them like the input. You should order them first by price and break the same price by distance.