import sys sys.setrecursionlimit(10 ** 7) import pypyjit pypyjit.set_param('max_unroll_recursion=-1') n=int(input()) a=list(map(int,input().split())) def f(x): x=set(x) x=list(x) if len(x)<=2: return x x.sort() a=x[1]-x[0] b=x[2]-x[1] if a==b: return x[:2] if a