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2

Part of 2018 Iran MO (2nd Round)

Problems(1)

Iranian Second Round P2

Source: Iran 2nd-round MO 2018 - P2

4/26/2018
Let nn be odd natural number and x1,x2,⋯ ,xnx_1,x_2,\cdots,x_n be pairwise distinct numbers. Prove that someone can divide the difference of these number into two sets with equal sum. ( X={∣xi−xj∣∣i<j}X=\{\mid x_i-x_j \mid | i<j\} )
combinatoricsIran