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Time Limit: 1.0 Seconds Memory Limit: 65536K

Total Runs: 1483 Accepted Runs: 529 Multiple test files

Always bored with cud-chewing, the cows have invented a new game.
One cow retrieves a set of *N* (3 ≤ *N* ≤ 20) hay bales from the shed
each of which is one unit high. Each bale also has some unique width
and unique breadth. ### Input

* Line 1: A single integer, *N* ### Output

* Line 1: The height of the tallest possible tower that can legally be
built from the bales.
### Sample Input

### Sample Output

### Input Details

Six bales of various widths and breadths ### Output Details

These bales can be stacked for a total height of 5:
[another stacking exists, too]

A second cow tries to choose a set of bales to make the tallest stack of bales in which each bale can be placed only on a bale whose own width and breadth are smaller than the width and breadth of the bale below. Bales can not be rotated to interchange the width and breadth.

Help the cows determine the highest achievable tower that can be legally built form a set of bales.

* Lines 2..*N* + 1: Each line describes a bale with two space-separated
integers,respectively the width and breadth

6 6 9 10 12 9 11 8 10 7 8 5 3

5

10 12 9 11 8 10 6 9 5 3

Maintance:Fxz. Developer: SuperHacker, G.D.Retop, Fxz