Next Customer Ticket

You are given a list of integers representing ticket numbers in a queue. A ticket number of -1 indicates that the ticket was cancelled. Your task is to output the first ticket number that is not cancelled. If all tickets are cancelled, output \(-1\).

For example, if the input is:

1 2 -1 4 5

Then the output should be:

1

Note that the input will be provided as a single line from standard input and the output should be printed to standard output.

inputFormat

The input consists of a single line of space-separated integers, where each integer represents a ticket number. A ticket number of -1 means that the corresponding ticket has been cancelled.

For example:

1 2 -1 4 5

outputFormat

Output a single integer: the ticket number that will be served next (the first ticket that is not -1). If all tickets are cancelled, output \(-1\).

## sample

1 2 -1 4 5

1