RETO1M10 - 5RETO 10 MARATON

Polycarpus loves television series. Now he's ready to finish watching a season of a popular comedy "Graph Theory". In total, the season has n episodes, numbered with integers from 1 to n numbers.

Polycarpus has not observed episodes one by one, but in a random order. You've seen every episode except one. What episode forgot Polycaprus to see?

Input

The first line of the input contains an integer n (2 ≤ n ≤ 100 000) - the number of episodes in a season. Suppose that the episodes are numbered by integers from 1 to n.

The second line contains n - 1 integers, a1, a2 ... an (1 ≤ ai ≤ n). The numbers of the episodes that Polycarpus has seen. All ai values are different.

Output

Print episode number Polycarpus has not seen.

Example

Input:
10
3 8 10 1 7 9 6 5 2

Output:
4

Added by:MARATON AFDM
Date:2015-09-28
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:MAWK BC C NCSHARP CSHARP C++ 4.3.2 CPP14 COFFEE DART FORTH JAVA JS-RHINO JULIA KTLN NODEJS OCT PHP PROLOG PYPY3 R RACKET SQLITE SWIFT UNLAMBDA

hide comments
2015-09-29 02:34:24 Francky
All problems of the user moved to tutorial.
@psetter : please solve some tasks here ; don't use unnecessary language restrictions ; choose carefully tutorial/classical section for each problem.
@all : if one of these problems could go back to classical, please mention it with requirements to make it decent.
2015-09-28 23:33:17 Scape
Please stop spamming with trivial tutorial problems.
2015-09-28 13:47:13 wisfaq
unnecessary language restrictions
tutorial problem
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