In the Bargain Bazar everyone purchase with a fair bargaining, so the traders markup the prices too much. A trader marked up an article at Rs. M expected huge profit if it is sold on the marked price. But a customer purchased it at M/2 with his fine bargaining skills, so the expected profit of the trader diminished by 66.66%. What is the percentage discount fetched by the customer through bargaining?

• 33.33 %
• 50%
• 66.66%
• none of these