Do you understand?

Just want a snake 1234.

We regard it as a row.

One in the first row

Two in the second row

etc

How many lines can reach 195?

Line 20

From one to nineteen, you get 190.

afterwards

The first row doesn't count

The second row is big on the left and small on the right.

The third row is small on the left and big on the right.

etc

Even the row on the left is big.

Odd lines are small on the left.

So 195 is the fifth from the bottom of the twentieth line.

Then we will forward the map to 19 1, which should be the 20th in the first row after forwarding.

192 second row 19.

193 divided into three rows 18.

194 divided into four rows 17.

195

Row 5 16

end