CF845A.Chess Tourney

普及/提高-

通过率:0%

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题目描述

Berland annual chess tournament is coming!

Organizers have gathered 2n2·n chess players who should be divided into two teams with nn people each. The first team is sponsored by BerOil and the second team is sponsored by BerMobile. Obviously, organizers should guarantee the win for the team of BerOil.

Thus, organizers should divide all 2n2·n players into two teams with nn people each in such a way that the first team always wins.

Every chess player has its rating rir_{i} . It is known that chess player with the greater rating always wins the player with the lower rating. If their ratings are equal then any of the players can win.

After teams assignment there will come a drawing to form nn pairs of opponents: in each pair there is a player from the first team and a player from the second team. Every chess player should be in exactly one pair. Every pair plays once. The drawing is totally random.

Is it possible to divide all 2n2·n players into two teams with nn people each so that the player from the first team in every pair wins regardless of the results of the drawing?

输入格式

The first line contains one integer nn ( 1<=n<=1001<=n<=100 ).

The second line contains 2n2·n integers a1,a2,... a2na_{1},a_{2},...\ a_{2n} ( 1<=ai<=10001<=a_{i}<=1000 ).

输出格式

If it's possible to divide all 2n2·n players into two teams with nn people each so that the player from the first team in every pair wins regardless of the results of the drawing, then print "YES". Otherwise print "NO".

输入输出样例

  • 输入#1

    2
    1 3 2 4
    

    输出#1

    YES
    
  • 输入#2

    1
    3 3
    

    输出#2

    NO
    
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