Based on the error message and the issue description, I can understand the problem. When Python 2 pickles a sympy Float expression, it saves the mantissa as a hex string that includes the `L` suffix for long integers (e.g., `'1L'`). When Python 3 tries to unpickle this, it fails because Python 3's `int()` function doesn't accept the `L` suffix.

The error occurs at line 1045 in `sympy/core/numbers.py`:
```python
num[1] = long(num[1], 16)
```

When `num[1]` is `'1L'` (a Python 2 long literal string), Python 3 can't parse it.

The fix needs to strip the trailing `L` from the hex string before converting it to an integer.

Here's the patch:

--- a/sympy/core/numbers.py
+++ b/sympy/core/numbers.py
@@ -1042,7 +1042,9 @@ class Float(Number):
             # it's a hexadecimal (coming from a+pickle)
             # assume that it is in standard form
             num = list(num)
-            num[1] = long(num[1], 16)
+            # handle the leading digit for Python 2 compatibility
+            # strip any 'L' suffix from Python 2 long integer repr
+            num[1] = long(num[1].rstrip('L'), 16)
             _mpf_ = tuple(num)
         else:
             if len(num) == 4: