import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[] A = {9,8,7};
        System.out.println(findOddStream(A)); // 6
        System.out.println(findOddImperative(A)); // 6

        int[] B = {7,8,9};
        System.out.println(findOddStream(B)); // 6
        System.out.println(findOddImperative(B)); // 6
    }

    static int findOddStream(int[] A) {
        return Arrays.stream(A).reduce(0, (a, b) -> a ^ b);
    }

    static int findOddImperative(int[] A) {
        int n = 0;
        for (int i:A) n^=i;
        return n;
    }
}