IN THE FOLLOWING 5 5 × SQUARE GRID, THE NUMBERS 1, 2, 3, 4 AND...

17. In the following 5 5 × square grid, the numbers 1, 2, 3, 4 and 5 are filled in,

such that each number appears only once in each row and only once in each

column. Find the number filled in the shaded square.

1 2

1

4

2 5

5 4