What does 1 mean?

When drawing lots, the seeds of 1 and No.2 are divided into the upper and lower parts, and then the seeds of 3 and 4 are separated and filled in in turn.

Then let the unseeded players play.

In sports events, because of the large number of participants, the elimination system is often used to shorten the competition time. In this way of competition, in order to prevent high-level players from being eliminated when they meet in the preliminary round, they are divided into different groups, and these players are called "seed players". Seed players are determined according to the performance of each player between the last competition and this competition.

The number of seed players is still uncertain. There may be different seed players in different competitions. For example, there are generally 32 seeded players in a tennis grand slam, and 64 such general competitions may only have 16 seeded players.