import java.util.*;
import java.util.stream.*;
class Ideone {
public static void main (String[] args) {
    int[] sequence = {1, 3, 2, 4, 3, 5, 4, 6, 1, 3};
    List<Integer> list = new ArrayList<>();
    IntStream.of(sequence).forEach(list::add);
    int index = list.subList(1, list.size()).indexOf(sequence[0]) + 1;
    System.out.println(index);
	
}
}