## Jenny Ye and John Wittrock

def manageGrades():
    grades = []
    x = input("Enter a grade, or -1 to exit: ")
    firstFreq=0
    secondFreq=0
    thirdFreq=0
    fourthFreq=0
    fifthFreq=0
    while x != -1:
        if 0 <= x <= 64:
            firstFreq +=1
        elif 65 <= x <= 69:
            secondFreq +=1
        elif 70 <= x <= 79:
            thirdFreq +=1
        elif 80 <= x <= 89:
            fourthFreq +=1
        elif 90<= x <=100:
            fifthFreq +=1
        grades += [x]
        x = input("Enter a grade, or -1 to exit: ")
    print " \n         STATS!"
    gradesSummary(grades)
    print "Histogram:"
    print "Interval         Frequency"
    print "90 - 100",'       ',`fifthFreq`
    print "80 - 89",'        ',`fourthFreq`
    print "70 - 79", '        ',`thirdFreq`
    print "65 - 69",'        ',`secondFreq`
    print "0 - 64",'         ',`firstFreq`
    
def medianGrade(x):
    ans = ""
    if len(x) % 2 ==1:
        ans += `x[len(x)/2 ]`
    else:
        ans += `(x[len(x)/2 -1] + x[len(x)/2 ])/2.0`
    print "The median grade is", ans+'.'

def highestGrade(x):
    print "The highest grade is", `x[-1]` + '. Nice.'
def lowestGrade(x):
    print "The lowest grade is", `x[0]` + '. Haha.'

def meanGrade(x):
    sum = 0
    i=0
    items = 0
    while i< len(x):
        items +=1
        sum+= x[i]
        i+=1
    print "The mean grade is", `sum/float(items)`
    
def gradesSummary(x):
    x.sort()
    print "Entered grades:" + `x`
    highestGrade(x)
    lowestGrade(x)
    medianGrade(x)
    meanGrade(x)

                     
manageGrades()