Update lancalc/main.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: wachawo

lancalc/main.py

@@ -259,7 +259,7 @@ def validate_prefix(prefix_str: str) -> int:
     try:
         p = int(prefix_str)
     except ValueError:
-        raise ValueError(f"Invalid prefix format: {prefix_str}")
+    p = int(prefix_str)
 
     if not 0 <= p <= 32:
         raise ValueError(f"Prefix must be between 0 and 32, got: {p}")