35. In the cells of a $9 \times 9$ square, non-negative numbers are placed. The sum of the numbers in any two adjacent rows is at least 20, and the sum of the numbers in any two adjacent columns does not exceed 16. What can the sum of the numbers in the entire table be?

(A. Chukhnov)
35. The total sum is no less than $4 \cdot 20=80$ (since the entire table is divided into 4 pairs of columns) and does not exceed $5 \cdot 16=80$ (since the table is covered by five pairs of rows with an overlap at the 8th row), therefore it is equal to 80.