a = '00112233445566778899'
num_lis = [int(i) for i in a]
if 0 not in set(num_lis) and len(set(num_lis))==9:
    print 10
else:
    dict1=[0 for i in range(10)]
    #num_lis.sort()
    for i in num_lis:
        dict1[i] = dict1[i]+1
    dict1[0]=max(dict1)+1
    #print min(dict1),dict1.index(min(dict1))
    print int((1+min(dict1))*str(dict1.index(min(dict1))))