PROGRAMMING:Count the number of leap years

The current Gregorian calendar's intercalation rules can be summarized as: four intercalations, one hundred non intercalations, four hundred intercalations. Programming: input a year, find out how many leap years have passed by the end of the year, limit can't use cycle structure. Suppose the Gregorian calendar was applied from the first day A.D（ Tip: find out how many 4 years, how many 100 years and how many 400 years you have experienced.)
###Input format:
Enter a positive integer for the year.
###Output format:
Output the number of leap years, and finally wrap.
###Input example:
```in
two thousand and twenty
```
###Output example:
The corresponding output is given here. For example:
```out
four hundred and ninety
```







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