You should check for a leap year separately from the last if statement (on line 82). The way you have it now it will only generate output if the year is a leap year. You could add a bit to your if statement that validates the day to consider when month == 2 and if it is a leap year. You could also add return statements to the if statements so that the program terminates when an invalid value is entered. For example (pseudo code):
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if (1 <= day <= 31)
if (month = 2)
if (year is a leap year)
if (day > 29)
print "Invalid day"elseif (day > 28)
print "Invalid day"