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Define the contract payoff
A call holder payoff per unit is max(S−K,0); a put holder payoff is max(K−S,0). Here S is the nonnegative terminal price and K the positive strike. The contract payoff remains a nonnegative holder amount.
Apply the side and quantity
Signed settlement is qUh. Initiation premium cash flow is −qUπ, where π is the nonnegative per-unit premium. Simple profit is their sum.
h is the holder payoff; premium is not financed to expiry.
Solve the positive-premium profit crossing
For a call the strike/premium boundary is K+π. For a put it is K−π if nonnegative. If π exceeds K, a put holder cannot recover that premium from any nonnegative terminal price under the simple model.
Handle zero premium carefully
When π = 0, simple profit equals signed payoff. A call has zero profit throughout S≤K and a put throughout S≥K, so K is a boundary of a zero region rather than a unique isolated breakeven point.