Calculate the age difference between two people from their date of birth
Enter the date of birth of the two people and click "Calculate age difference" to calculate the age difference between the two entered.
The age difference is displayed by year, month, day, number of months, days, etc., and is displayed when the first day is set to 0 and when it is set to 1.
In addition, the grade difference between the two students is also displayed.
Grade difference is calculated as premature birth if born between January 1st and April 1st.
