CC Level Splicer

in_name = raw_input('Input file name?: ')
with open(in_name) as f:
    for i, l in enumerate(f):
        pass
input_f = open(in_name,'r')
out_name = raw_input('Output file name?: ')

levels = input_f.read().split('\n')
output_buffer = b'\xac\xaa\x02\x00' + chr(i + 1)+ b'\x00'

failed = False

for x in levels:
    pair = x.split('\t')
    level_f = open(pair[0],'rb')
    level_f.seek(4, 0)
    num_levels = ord(level_f.read(1)) + 256*ord(level_f.read(1))
    while (True):
        lb = level_f.read(1) + level_f.read(1)
        ln = level_f.read(1) + level_f.read(1)
        num_bytes = ord(lb[0]) + ord(lb[1])*256
        level_num = ord(ln[0]) + ord(ln[1])*256
        if (level_num == int(pair[1])):
            level_bytes = level_f.read(num_bytes-2)
            output_buffer += (lb + ln + level_bytes)
            break
        level_f.seek(num_bytes-2,1)
        if (level_num == num_levels):
            failed = True
            break
    level_f.close()

input_f.close()

if (not failed):
    output_f = open(out_name,'wb')
    output_f.write(output_buffer)
    output_f.close()
    print "Success"
else:
    print "Failure"