If statement exercise, if statement

If statement exercise, if statement

Enter the year, month, and day. First, judge that the year is a year or a year, and calculate that the day is the day of the year:

Determine whether the weight of men and women is standard:

There is a problem in weight determination: if the gender is not entered into the male or female, "enter the correct gender" will be output, and "XXX: your weight ......" In order to output "Please enter the correct gender" and then stop running, you can only set another if outside the next if. It still needs to be improved, but I don't know how to write it ......