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Time Limit: 1.0 Seconds Memory Limit: 65536K Special Judge

Total Runs: 841 Accepted Runs: 365 Multiple test files

Some people think that the bigger an elephant is, the smarter it is. To disprove this, you want to take the data on a collection of elephants and put as large a subset of this data as possible into a sequence so that the weights are increasing, but the IQ's are decreasing.

The input will consist of data for a bunch of elephants, one elephant per line, terminated by the end-of-file. The data for a particular elephant will consist of a pair of integers: the first representing its size in kilograms and the second representing its IQ in hundredths of IQ points. Both integers are between 1 and 10000. The data will contain information for at most 1000 elephants. Two elephants may have the same weight, the same IQ, or even the same weight and IQ.

Say that the numbers on the i-th data line are `W[i]` and `S[i]`.
Your program should output a sequence of lines of data; the first line should
contain a number `n`; the remaining `n` lines should
each contain a single positive integer (each one representing an elephant).
If these `n` integers are `a[1]`, `a[2]`,..., `a[n]`
then it must be the case that

andW[a[1]] < W[a[2]] < ... < W[a[n]]

S[a[1]] > S[a[2]] > ... > S[a[n]]

6008 1300 6000 2100 500 2000 1000 4000 1100 3000 6000 2000 8000 1400 6000 1200 2000 1900

4 4 5 9 7

**Note:** Special judge problem, you may get "Wrong Answer" when output in wrong format.

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