$162$ pluses and $144$ minuses are placed in a $30\times 30$ table in such a way that each row and each column contains at most $17$ signs. (No cell contains more than one sign.) For every plus we count the number of minuses in its row and for every minus we count the number of pluses in its column. Find the maximum of the sum of these numbers.
1. **Define the problem and variables:**
   - We have a \(30 \times 30\) table.
   - There are 162 pluses and 144 minuses.
   - Each row and each column contains at most 17 signs.
   - We need to find the maximum sum \(S\) of the counts of minuses in the rows of pluses and pluses in the columns of minuses.

2. **Calculate the total number of cells:**
   \[
   30 \times 30 = 900
   \]
   Since there are 162 pluses and 144 minuses, the total number of signs is:
   \[
   162 + 144 = 306
   \]
   This means 594 cells are empty.

3. **Constraints on rows and columns:**
   Each row and each column can have at most 17 signs. Therefore, the maximum number of signs in any row or column is 17.

4. **Arrangement strategy:**
   Consider an \(18 \times 18\) square with the top left to bottom right diagonal empty. This means there are \(18 \times 18 - 18 = 306\) cells available for signs, which matches the total number of signs we have.

5. **Placing the pluses and minuses:**
   - Arrange the 162 pluses in two \(9 \times 9\) squares, one in the top right corner and one in the bottom left corner.
   - Fill the remaining cells in the \(18 \times 18\) square with minuses.

6. **Verify the arrangement:**
   - Each row and each column in the \(18 \times 18\) square has exactly 17 signs.
   - Each row and each column has 9 pluses and 8 minuses.

7. **Count the contributions to \(S\):**
   - For each minus, count the number of pluses in its row. Each minus sees 9 pluses in its row.
   - For each plus, count the number of minuses in its column. Each plus sees 8 minuses in its column.

8. **Calculate the total sum \(S\):**
   - Each of the 144 minuses counts 9 pluses:
     \[
     144 \times 9 = 1296
     \]
   - Each of the 162 pluses counts 8 minuses:
     \[
     162 \times 8 = 1296
     \]
   - Therefore, the total sum \(S\) is:
     \[
     S = 1296 + 1296 = 2592
     \]

9. **Conclusion:**
   The maximum value of \(S\) is \(2592\).

The final answer is \(\boxed{2592}\).