Task: Question Generation
Input (English): Passage: During the early reign of the Yongle Emperor, the territorial princes were restored of their positions. However, they were relocated away from the frontiers, and gradually stripped of their military power. With the subsequent policies enforced by the Yongle Emperor, the emperor was successful in consolidating the power of the central government. In 1426, the Xuande Emperor managed to force all of the territorial princes to renounce their remaining personal army after suppressing the rebellion of Zhu Gaoxu. The Yongle Emperor began the preparation for relocating the imperial capital to Beiping in 1403, a process that lasted throughout his entire reign. The construction of the future Forbidden City along with the restructuring of the Grand Canal were constantly ongoing. In 1420, the reconstruction of Beiping City was completed, and the Ming Dynasty officially relocated the imperial capital to Beiping and renamed the city to Beijing. With the exception of Republic of China between 1928 and 1949, Beijing remains to be the fixed capital of China ever since.
Output (English): How many years after Yongle Emperor began the preparation for relocating the imperial capital to Beiping was the reconstruction complete?