Task 1. Costa, Jane, and Vladimir planted trees: a pear, an apple, and a cherry. Each planted one tree, whose name does not start with the same letter as their own name. Who planted which tree, given that Vladimir did not plant the pear?
Solution. By completing the table, it is obtained that Costa planted a cherry, Ivan a pear, and Vladimir apples.

|  | pear | apples | cherry |
| :--- | :--- | :--- | :--- |
| Costa | - | - | + |
| Ivan | + | - | - |
| Vladimir | - | + | - |