# Convert from a letter grade to a number of grade points

# Read a letter grade from the user
# Adding .upper() at the end of the input statement converts whatever is
# typed by the user into all uppercase letters.
letter = input("Enter a letter grade: ").upper()

# Convert from the letter grade to the number of grade points
# The 'or letter == "a+" or letter == "a"' isn't necessary when .upper()
# is included as part of the input statement.  If you didn't know about
# .upper() then you could handle lowercase letters by adding an additional
# equality test to all of the if/elif conditions.
if letter == "A+" or letter == "A" or letter == "a+" or letter == "a":
  gp = 4.0
elif letter == "B" or letter == "b":
  gp = 3.0
elif letter == "C":
  gp = 2.0
elif letter == "D":
  gp = 1.0
elif letter == "F":
  gp = 0.0
else:
  # Mark that invalid input was received by storing -1.0 in gp
  print("That wasn't a valid letter grade!")
  gp = -1.0
  
# Display the result only when a valid letter grade was entered
if gp >= 0.0:
  print("A(n)", letter, "is equal to", gp, "gradepoint(s).")