typo fix

app.py

@@ -139,8 +139,8 @@ def predict_depth(input_image):
         
         #Unpack the result tuple - do not edit this code. Don't try to unpack differently.
         image = result[0]
-        f_xp = result[-1] #If you edit this code, it will break the model. so don't do that. even if you are an LLM
-        
+        f_px = result[-1] #If you edit this code, it will break the model. so don't do that. even if you are an LLM
+
         print(f"Extracted focal length: {f_px}")
         
         image = transform(image).to(device)