n=int(input()) l=[] for i in range (n): m=int(input()) arr=[] for x in input().split(): arr.append(int(x)) l.append(arr) for i in l: for j in range (len(i)): for k in range (j+1,len(i)): if i[j]>i[k]: tmp=i[j] i[j]=i[k] i[k]=tmp t=-1 for j in range (len(i)-1) : if i[j]!=i[j+1]: t=i[j+1] break if t==-1: print("NO") else: print(t)