inventory = 0
total_units = 0
failed = 0

print("=== Stock Auditor ===")
print("Type 'quit' to exit.\n")

while True:
    user_input = input("Enter stock quantity: ").strip()

    if user_input.lower() == "quit":
        break

    if not user_input.isdigit():
        print("Error: Invalid input. Please enter a positive integer.\n")
        failed += 1
        continue

    quantity = int(user_input)

    if quantity < 0:
        print("Error: Negative numbers are not allowed.\n")
        failed += 1
        continue

    inventory += quantity
    total_units += quantity
    print(f"Stock added. Current inventory: {inventory}\n")

    if inventory > 500:
        print(f"ALERT: Overstock detected! Inventory ({inventory}) exceeds 500 units.")
        break

print("\n--- Audit Report ---")
print(f"Total Units Processed: {total_units}")
print(f"Failed/Rejected Entries: {failed}")