25206.py

sum = 0
hakjum_sum = 0
for _ in range(20):
  name, hakjum, grade = input().split()
  if grade == "A+":
    grade = 4.5
  elif grade == "A0":
    grade = 4.0
  elif grade == "B+":
    grade = 3.5
  elif grade == "B0":
    grade = 3.0
  elif grade == "C+":
    grade = 2.5
  elif grade == "C0":
    grade = 2.0
  elif grade == "D+":
    grade = 1.5
  elif grade == "D0":
    grade = 1.0
  elif grade == "F":
    grade = 0.0
  elif grade == "P":
    continue
  sum += float(hakjum)*grade
  hakjum_sum += float(hakjum)

print(sum/hakjum_sum)