from datetime import date
curr_date=date.today()
while True:
    try:
        age=int(input('How Old Are You?'))
    except ValueError:
        print('please enter your age')
    else:
        break
req_age=100-age
year_for_hundered_years=int(curr_date.strftime('%Y'))+req_age
print('You\'ll be 100 years old in ',year_for_hundered_years)