C. 642.

(5 points)

Deadline expired.

Statistics on problem C. 642. 560 students sent a solution. 5 points: 293 students. 4 points: 121 students. 3 points: 50 students. 2 points: 18 students. 1 point: 18 students. 0 point: 59 students. Unfair, not evaluated: 1 solution.