What is the oath that the president must say?

Every president starting with George Washington has said the same oath at his inauguration:

"I do solemnly swear that I will faithfully execute the office of president of the United States, and will, to the best of my ability, preserve, protect, and defend the Constitution of the United States." The president customarily adds "So help me God."

that is alot i do not no

because the early people found out about it.