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Problem

A tree with n nodes numbered from 1 to n is represented by

the parent array t. For each node i, the value t[i] is the

parent of node i, and t[i] = 0 means that node i is the root

of the tree.

Write a program that reads n and then the n values of the parent

array, and prints the index of the root.

Input format

Input input.txt

The first line contains the natural number `n`. The second line contains `n` non-negative integers separated by spaces, representing the values `t[1], t[2], ..., t[n]` of the parent array. - `1 <= n <= 100` - `0 <= t[i] <= n` for every `i` in `1..n` - the array describes a valid tree, so there is exactly one value equal to `0`

Output format

Output output.txt

The program prints a single natural number: the index of the root.

Example

input
7

2 4 4 0 4 5 5
output
4

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