Suppose you buy a call option with strike price K1 and sell a call option on the same stock with the same expiration date but with a strike price of K2, where K2 > K1. Write an expression for the payoff of this options portfolio and draw the payoff diagram (ignoring the premiums on the two options). Is the initial cost of this portfolio positive or negative?

Let S = stock price, M_T = payoff

For the payoff diagram, let X-axis be the current stock price, and let Y-axis be the payoff