Kermesse

The senior students decided to organize a bazaar to raise funds for the graduation party. The party promised to be a success, because the father of one of the trainees, Theophilus, who owns a computer store, decided to donate a computer to be raffled among those who attend. Students prepared mulled wine stalls, popcorn, candy, rehearsed the gang and put on sale tickets numbered sequentially from 1. The ticket number would serve to draw the computer. It was agreed that Theophilus would decide the draw method; in principle the draw would be, of course, computerized.

The venue for the party was the school gym. The entrance of the participants was the main door, which has a wheel where a person spends at a time. At the entrance, an employee entered in a list in school computer, the ticket number, in order of arrival of the participants. After the input of all participants, Theophilus began working on the computer to prepare the draw. Checking the list of gifts, he noticed a notable feature: there was only one case in the entire list, the participant that had the numbered ticket with i, was the ith person to enter the gym. Theophilus was so delighted by the coincidence that decided that the draw would not be necessary: this person would be the winner of the computer.

Knowing the list of participants, in order of arrival, your task is to determine the winning ticket number, knowing that the winner is the only participant who has the ticket number equal to its input position in the party.