One day, in a remote lesson via some kind of video conferencing service, the teacher noticed that one of the
N students in the class was missing. To understand who exactly is missing, the teacher asked each student present to write in the chat his number in the class journal: a number from
1 to
N. Then, after the end of the lesson, by viewing the saved chat, the teacher will be able to understand which of the students did not write his number. Help him - write a program that will do it.
Input
The first line of the input contains an integer
N (1 <= N <= 10
5 ) — the number of students in the class. The following
N-1 lines contain one number each — the numbers of the students present at the lesson in random order. Among these numbers, every number from
1 to
N, except for one, occurs exactly once.
Imprint
The program should output a single number — number of the missing student.
Examples
| # |
Input |
Output |
| 1 |
5
2
5
1
3 |
4 |