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MMO 336 Moscow MO 1956 64 numbers with 1956 sum, square table

Source:

August 19, 2019
Sumcombinatoricsalgebra

Problem Statement

6464 non-negative numbers whose sum equals 19561956 are arranged in a square table, eight numbers in each row and each column. The sum of the numbers on the two longest diagonals is equal to 112112. The numbers situated symmetrically with respect to any of the longest diagonals are equal.
(a) Prove that the sum of numbers in any column is less than 10351035.
(b) Prove that the sum of numbers in any row is less than 518518.