Probably because of the controversial fifteenth-century antipope known as John XXIII, this name was avoided for over 500 years until the election in 1958 of Pope John XXIII. Immediately after John XXIII's election as pope in 1958, it was not known if he would be John XXIII or XXIV; he decided that he would be known as John XXIII. The number used by an antipope is ignored if possible, but this is not possible if, by the time someone is reckoned as antipope, the name has since been used by one or more legitimate popes (e.g. Benedict X was later reckoned as antipope).