Update fs.py

fs.py

@@ -170,18 +170,20 @@ class Fs(datasets.GeneratorBasedBuilder):
                 row = json.loads(line)
 
                 prefix, addition = row["source"].strip(), "Summary:"
-                input_length = len(tokenizer.encode(prefix + "\n" + addition))
-
+                encoded_input = tokenizer.encode(prefix + "\n" + addition)
+                input_length = len(encoded_input)
+                
                 n_truncations = 0
                 while input_length > max_source_length:
-                    overflow = len(tokenizer.encode(prefix + "\n" + addition)) - max_source_length
+                    overflow = input_length - max_source_length
                     tokenized_prefix = tokenizer.encode(prefix, add_special_tokens=False)
                     if overflow > 0:
                         tokenized_prefix = tokenized_prefix[:-overflow]
                     n_truncations += 1
                     prefix = tokenizer.decode(tokenized_prefix, skip_special_tokens=False).strip()
-                    input_length = len(tokenizer.encode(prefix + "\n" + addition))
-
+                    encoded_input = tokenizer.encode(prefix + "\n" + addition)
+                    input_length = len(encoded_input)
+                    
                 valid_input = prefix + "\n" + addition
 
                 row["input"] = valid_input