CF271A.Beautiful Year

It seems like the year of 2013 came only yesterday. Do you know a curious fact? The year of 2013 is the first year after the old 1987 with only distinct digits.

Now you are suggested to solve the following problem: given a year number, find the minimum year number which is strictly larger than the given one and has only distinct digits.

The single line contains integer $y$ $(1000<=y<=9000)$ — the year number.

Print a single integer — the minimum year number that is strictly larger than $y$ and all it's digits are distinct. It is guaranteed that the answer exists.