There is one number, and there are three numbers in the second line. . . . .

(per line

Odd numbers are negative and even numbers are positive)

The number in each line is arithmetic progression 1~ 19. There are 37 numbers in each row of 1, 3, 5, 7 and ..........., and the sum of the numbers in each row is exactly the last number in the last row.

The last number in line 19 is: x=( 1+37) times the number of items 19 and then divided by 2=36 1.

So the first number in line 20 is 362.

then

-363

The third number is

364