diff --git a/NER_IDCNN_CRF/data_utils.py b/NER_IDCNN_CRF/data_utils.py
index 71d7c21..a7fe708 100644
--- a/NER_IDCNN_CRF/data_utils.py
+++ b/NER_IDCNN_CRF/data_utils.py
@@ -290,7 +290,7 @@ def sort_and_pad(self, data, batch_size):
         sorted_data = sorted(data, key=lambda x: len(x[0]))
         batch_data = list()
         for i in range(num_batch):
-            batch_data.append(self.pad_data(sorted_data[i*batch_size : (i+1)*batch_size]))
+            batch_data.append(self.pad_data(sorted_data[int(i*batch_size) : int((i+1)*batch_size)]))
         return batch_data
 
     @staticmethod