#Problem 1
print('Problem 1')

n = int(input('Enter an integer '))
result = (1+n**2)/(1+n**3)
print(result)
print(5*'\n')

#Problem 2
print('Problem 2')
user_input = float(input('Enter a distance in miles '))
print('The distance is', user_input*1.60934)
print(5*'\n')

#Problem 3
print('Problem 3')

user_input = int(input('Enter an integer '))
discriminant = n**3+n**2+1
if discriminant % 7:  #divisible by 7
    print('It is')
else:
    print('It is not')
print(5*'\n')

#Problem 4
print('Problem 4')

user_input = int(input('How many points (out of 160) did the student score? '))
percentage = user_input/160*100
if percentage > 90:
    print('A')
elif percentage > 80:
    print('B')
elif percentage > 65:
    print('C')
elif percentage > 55:
    print('D')
else:
    print('F')