diff --git a/problem/models.py b/problem/models.py
index 8b373b0..61cc8f4 100644
--- a/problem/models.py
+++ b/problem/models.py
@@ -63,11 +63,11 @@ class AbstractProblem(models.Model):
         abstract = True
 
     def add_submission_number(self):
-        self.total_submit_number=models.F("total_submit_number") + 1
+        self.total_submit_number = models.F("total_submit_number") + 1
         self.save()
 
     def add_ac_number(self):
-        self.total_accepted_number=models.F("total_accepted_number") + 1
+        self.total_accepted_number = models.F("total_accepted_number") + 1
         self.save()
 
 
diff --git a/problem/tests.py b/problem/tests.py
index fc9fa44..0aeefb0 100644
--- a/problem/tests.py
+++ b/problem/tests.py
@@ -29,7 +29,8 @@ class TestCaseUploadAPITest(APITestCase):
         self.create_super_admin()
 
     def test_filter_file_name(self):
-        self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in", ".DS_Store"], spj=False), ["1.in", "1.out"])
+        self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in", ".DS_Store"], spj=False),
+                         ["1.in", "1.out"])
         self.assertEqual(self.api.filter_name_list(["2.in", "2.out"], spj=False), [])
 
         self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in"], spj=True), ["1.in", "2.in"])
diff --git a/problem/views/oj.py b/problem/views/oj.py
index bed7ed8..ffce405 100644
--- a/problem/views/oj.py
+++ b/problem/views/oj.py
@@ -1,4 +1,4 @@
-from django.db.models import Q, Count
+from django.db.models import Q
 from utils.api import APIView
 
 from ..models import ProblemTag, Problem