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Witnesses, numbered from to , have made their testimonies in a court. Each testimony is a statement of the form: “the -th witness agrees with the -th witness” or “the -th witness does not agree with the -th witness”.

If the -th witness agrees with the -th witness then he agrees also with all the witnesses that the -th witness agrees with. Similarly, the -th witness does not agree with all the witnesses that the -th witness does not agree with. We assume that every witness implicitly states: “I agree with myself”.

We say that witness is not credible if from testimonies made in a court it follows that there exists a witness such that agrees with and does not agree with .

Write a program that:

- reads the number of witness and their testimonies from the standard input,
- finds all the witnesses that are not credible,
- writes the result to the standard output.

In the first line of the standard input there is a single integer , , which is the number of witnesses. In the second line there is a single integer , , which is the number of testimonies.

In each of the following lines there are two integers (, ), separated by a single space. If is positive it describes a testimony: “the -th witness agrees with the -th witness”. If is negative it means: “the -th witness does not agree with the -th witness”.

In the standard output there should be written:

- a single word
`NIKT`(which means “nobody” in Polish), if it follows from testimonies that there is no witness that is not credible, - or — in increasing order — the numbers of witnesses that are not credible (one member in one line).

For the input data:

6 12 1 3 1 6 2 -1 3 4 4 1 4 -2 4 5 5 -1 5 -3 5 2 6 5 6 4

the correct result is:

1 3 4 6

*Task author: Grzegorz Jakacki.*