PROGRAMMING:Function returns whether a date is a legal date

Write a function. The formal parameter is three integers representing month, year and day. The function returns whether the date is legal. Enter three integers of a date in the main function. If it is a legal date, output yes, otherwise output No.
###Input example:
```in
2050 10 5
```
###Output example:
```out
YES
```
###Input example:
```in
2050 2 29
```
###Output example:
```out
NO
```






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