Date Format Conversion

You are given a series of dates, each in one of the following formats:

• \( YYYY/MM/DD \)
• \( MM-DD-YYYY \)
• \( DD.MM.YYYY \)

Your task is to read the dates from standard input until you encounter a line containing the word end (case-sensitive). For each valid date, convert it into the standardized format \( YYYY-MM-DD \) and print it to standard output on a separate line. If a date is given in an unsupported or invalid format, skip it.

For example, if the input is:

2023/10/14
04-15-2021
30.09.2020
end

the output should be:

2023-10-14
2021-04-15
2020-09-30

inputFormat

The input consists of several lines. Each line (except the termination line) contains a date in one of the supported formats. The input is terminated by a line containing only end.

outputFormat

For each valid input date, output a line containing the date formatted as YYYY-MM-DD. Invalid or unsupported formats should not produce any output.

## sample

2023/10/14
04-15-2021
30.09.2020
end

2023-10-14
2021-04-15
2020-09-30

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