nptel assignment

grading = {
    # A, AB, B, BC, C, CD, D
    "A":10,
    "AB":9,
    "B":8,
    "BC":7,
    "C":6,
    "CD":5,
    "D":4
}
courses_arr = []
grades_arr = []
students = { } 
std_avg = {
    
}


inpt = input().split("~")

if inpt == ["Courses"]:
    while True:
        inpt = input().split("~")
        if inpt == ["Students"]:
            break
        course = { }
        course["Course Code"] = inpt[0]
        course["Course Name"] = inpt[1]
        course["Semester"] = inpt[2]
        course["Year"] = inpt[3]
        course["Instructor"] = inpt[4]
        courses_arr.append(course)
   
if inpt == ["Students"]:
    while True:
        inpt = input().split("~")
        if inpt == ["Grades"]:
            break
        
        students[inpt[0]] = inpt[1]
            
if inpt == ["Grades"]:
    # Course Code~Semester~Year~Roll Number~Grade
    while True:
        inpt = input().split("~")
        if inpt == ["EndOfInput"]:
            break
        grades = { }
        inpt = input().split("~")
        grades["Course Code"] = inpt[0]
        grades["Semester"] = inpt[1]
        grades["Year"] = inpt[2]
        grades["Roll Number"] = inpt[3]
        grades["Grade"] = grading[inpt[4]]
        grades_arr.append(grades)
            
for i in grades_arr:
    roll = i["Roll Number"]
    grade = i["Grade"]
    if roll in std_avg:
        std_avg[roll][1] += grade
        std_avg[roll][2] += 1
    else:
        std_avg[roll] = [students[roll],grade,1]
        
arr = []

for i,k in std_avg.items():
    arr.append([i,k[0],round(k[1]/k[2],2)])
    
arr.sort()
for i in arr:
    print(i[0]+"~"+i[1]+"~"+str(i[2]))