The costs of appeal are assessed against the Defendants.

1. In order to cancel a sales contract on the grounds of nonperformance of obligations with respect to the grounds of appeal Nos. 1 through 4, such obligation shall be the principal obligation to the extent that the seller would not conclude the sales contract because the objective of the sales contract is not fulfilled, and if the obligation is not fulfilled, it shall be the principal obligation to the extent that the seller would not have concluded the sales contract. In distinguishing between the principal obligation and the incidental obligation of a large number of contractual obligations, regardless of the independent value of payment, it shall be determined by the reasonable will of the party expressed at the time of signing the contract, or by considering the circumstances clearly expressed at

(2) In light of the aforementioned legal principles, the Defendants are obligated to remove and cooperate with the Plaintiff as a seller of the instant sales contract in light of the following legal principles: (a) not only the Plaintiff, but also the Plaintiff as a seller of the instant sales contract, but also with the duty to remove and cooperate with respect to a series of procedures, such as new construction of buildings based on the right to remove a building within a development-restricted zone and permission for the installation of a parking lot attached thereto, so that the Plaintiff can use the instant land for repair store business; (b) the obligation is necessary to achieve the purpose of the sales contract; and (c) the Defendants’ performance assistant constitutes the principal obligation of the instant sales contract; and (d) D, an agent of the Defendants, should be released from the development-restricted zone for the Defendant’s residential area after the cancellation of the development-restricted zone for the Defendant’s residential area.