def find(n): a = input().split() a = [ int(x) for x in a] a = list(set(a)) #[1,1,1,1,1,1,2,4,5] ---?> [1,2,4,5] ---[1] a.sort() #从小到大的 if len(a)==1: print("NO") else: print(a[1]) m = int(input()) for x in range(m): n = int(input()) find(n)