Easy codeforces problem

this seems quite easy problem from codeforces can someone explain what does “all it’s digits are distinct” mean? what to calculate ??

Means find a number which does not have two digits equal… 2010 have ‘0’ twice which is not allowed…
2011 has ‘1’ twice which is not allowed…
2111 has ‘1’ thrice which is also not allowed
Where as 2056 has all digits at most once

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