while True:
    n=int(input())
    if n==0:
        break
    else:
        s=input().split()
        #print(s)
        s1=[]
        for n in s:
            #s2=list(map(str,n))
            s2=list(n)
            s2.sort()
##            print(s2)
            a="".join(s2)
            s1.append(a)
        #print(s1)
     
        s3=[]
        i=0
        while i<len(s1):
            if s1.count(s1[i])==1:
                s3.append(s[i])
            i+=1
            
        s3.sort()   
        if len(s3)==0:
            print("None")
        else:
            for tcase in s3:
                print(tcase,end=" ")
            print()