Duke Energy (DUK) has $80 million in excess cash and no debt. The firm expects to generate additional free cash flows of $60 million per ear in subsequent years and will pay out these future free cash flows as regular dividends. DUK's unlevered cost of capital is 12% and there are 10 million shares outstanding. Assume that DUK uses the entire $80 million to repurchase shares. What is the number of shares that DUK will repurchase