# Problem A

Best Before

Given a possibly ambiguous date “$A/B/C$”, where $A, B, C$ are integers between $0$ and $2999$, output the earliest possible legal date between Jan 1, 2000 and Dec 31, 2999 (inclusive) using them as day, month and year (but not necessarily in that order).

Recall that a year is a leap year (has 366 days) if the year is divisible by 4, unless it is divisible also by 100 but not by 400 (so 2000 is a leap year, 2100 is not a leap year, and 2012 is a leap year).

## Input

The input file consists of a single line containing three integers separated by “/”. There are no extra spaces around the “/”. Years may be truncated to two digits and may in that case also omit the leading $0$ (if there is one), so $2000$ could be given as “2000”, “00” or “0” (but not as an empty string). Months and days may be zero-padded. You may assume that the year, when given with four digits, is between $2000$ and $2999$. At most one of the integers has four digits, and the others have one or two digits.

## Output

Output a single line giving the earliest legal date possible
given the above constraints. The output should be formatted as
year-month-day, where year has four digits, and month and day
have two digits each (zero padding), for example “`2011-07-15`”.

If there is no legal date (subject to the above constraints)
then output a single line with the original string followed by
the words “`is illegal`”.

Sample Input 1 | Sample Output 1 |
---|---|

02/4/67 |
2067-02-04 |

Sample Input 2 | Sample Output 2 |
---|---|

31/9/73 |
31/9/73 is illegal |