Update app.py

app.py

@@ -51,12 +51,9 @@ def _noop(*args, **kwargs):
 gradio.utils.watchfn_spaces = _noop
 
 def validate_input(fen):
-    is_valid = True
+    fen_pattern = r'\b([rnbqkpRNBQKP1-8\/]+\s+[wb]\s+(?:-|[KQkq]+)\s+(?:-|[a-h][36])\s+\d+\s+\d+)\b'
 
-    if fen.len() > 100:
-        is_valid = False
-
-    return is_valid
+    return re.search(fen_pattern, fen)
 
 # Graphical user interface