I need your help very much!
Please give me some hints, how to solve this problem:
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There are n teams (2<=n<=1000, n is even). Every day all teams must play exactly one game. So each day, there will be n/2 games. i'th team must play just once with j'th team. The task is to create a schedule for n-1 days, so each team must play with another n-1 teams just once and have exactly one game per day!

For example:
If n=4,
answer may be:
*********
1st day:
1 2
3 4
2nd day:
1 3
2 4
3rd day:
1 4
2 3
*********

I'm very sorry for my poor english!