Unique identifiers exist if we check all 10 digits in this order`[0, 2, 4, 6, 8, 1, 3, 5, 7, 9]`

.

```
class Solution(object):
def originalDigits(self, s):
l, cnt, ret = [('zero','z'),('one','o'),('two','w'),('three','h'),('four','u'),('five','f'),('six','x'),('seven','s'),('eight','g'),('nine','i')], collections.Counter(s), []
for i in [0, 2, 4, 6, 8, 1, 3, 5, 7, 9]:
n = cnt[l[i][1]]
for c in l[i][0]:
cnt[c] -= n
ret += [str(i)]*n
return ''.join(sorted(ret))
```