n=int(input()) l=[] for i in range (n): x=int(input()) arr=[] for j in input().split(): arr.append(int(j)) l.append(arr) for i in l: for j in range(len(i)-1): for k in range(j+1,len(i)): if i[j]>i[k]: t=i[j] i[j]=i[k] i[k]=t min=i[0] count=0 for j in i: if j>min: min=j count+=1 if count==1: break if count==1: print(min) else: print("NO")