fork(1) download
  1. n = int(input())
  2. a = [int(input()) for x in range(n)]
  3. d = a[1] - a[0]
  4. print(d if str(a) == str([*range(a[0], a[0] + d*n, d)]) else 0)
Success #stdin #stdout 0.02s 9304KB
stdin
5
6
3
0
-3
-6
stdout
-3