Someone Please tell me what's wrong with the code-

general
,
1

Please tell me where’s my code for “Marks Discrepency” has gone wrong. It Works fine in my machine CodeChef: Practical coding for everyone

n = int(raw_input())

students =[0,0,0,0,0]

frequency = [{},{},{},{},{}]

for i in range(n):

x = raw_input() 

    subject = ord(x[0])-65

    students[subject] +=1

(frequency[subject])[x[2:]] = (frequency[subject]).get(x[2:],0) + 1

for i in range(5):

list = frequency[i]

unusual = []

    for j in range(len(list)):

    	if list[list.keys()[j]] / (students[i]*1.0) > 0.1 :

            	unusual = unusual + [list.keys()[j]]
            	
    if len(unusual) == 0:

    	print "Nothing Unusual"

    else :

            unusual.sort()

    	for k in range(len(unusual)):

    	       print unusual[k],

    	print ""