File "<string>", line SyntaxError: unexpected EOF while parsing - python-2.7

Question

I am trying to do this exercise but fail. I can only get this result:
main() File "C:\Users\chemuser\Desktop\KHL\python\chapter4_6.py", line 22, in main
asciimark = eval(line) File "<string>", line 1
^ SyntaxError: unexpected EOF while parsing
here is my fail code:
# -*- coding: cp1252 -*-
#A certain CS professor gives 5-point quizzes that are
#graded on the scale 5-A, 4-B, 3-C, 2-D, 1-F, 0-F.
#Write a program that accepts a quiz score as an
#input and prints out the corresponding grade.
import string
def main():
#set up file names
infileName = raw_input("input file name: ")
outfileName = raw_input("output file name: ")
#open files
infile = open(infileName, "r")
outfile = open(outfileName, "w")
#process each line of the input file
for line in infile.readlines():
#get the mark from line
asciimark = eval(line)
#creat grade
allgrade = "FEDCBA"
grade = allgrade[asciimark]
#write it to the output file
outfile.write(grade+"\n")
#close both files
infile.close()
outfile.close()
print "Done!"
main()
the input file is look like this (just a column of number 0 - 5, no blank line between):
5
1
0
2
3
I did a test, I add '/n' in the first line (5/n), it shows:
main() File "C:\Users\chemuser\Desktop\KHL\python\chapter4_6.py", line 22, in main
asciimark = eval(line) File "<string>", line 1
5\n
^ SyntaxError: unexpected character after line continuation character
your comments are very appreciated!!