a=int(input()) z=[] for i in range(a): b=int(input()) y=[] for j in input().split(): y.append(int(j)) for j in range(len(y)-1): for k in range(j+1,len(y)): if y[j]>y[k]: t=y[j] y[j]=y[k] y[k]=t s=y[0] for j in range(len(y)): if y[j]!=s: z.append(y[j]) break if j==len(y)-1: z.append("NO") break for i in z: print(i)