Write a program to calculate the number of days from January 1, 1970 to a specific date. If the date is invalid or earlier than January 1, 1970, output 0.
Rules of leap year:
A year not divisible by 4 is a common year.
A year divisible by 4 but not divisible by 100 is a leap year.
A year divisible by 400 is a leap year.
A year divisible by 1000 is a leap year.
A date.
Ex. 1970
1
5
The amout of days.
Ex. 5