13. Tennis Tournaments. In a tennis tournament, there are $n$ players. Each tennis player is eliminated from the tournament after their first loss. How many matches should be held to determine the winner?
13. After each match, one of the players is eliminated. Since in the end $n-1$ tennis players are eliminated, a total of $n-1$ matches should be held.

[F. Mapep, M. M., 23, 287 (May 1950).]