Third Maximum Distinct Number

/*
 * Problem : Third maximum.
 * Input   : n, then n integers.
 * Output  : One number.
 * Approach: Three variables.
 * Time    : O(n)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static long solve(int[] a) {
        // Step 1: Keep the three biggest different values seen so far. Long.MIN_VALUE means "not set yet".
        long first = Long.MIN_VALUE;
        long second = Long.MIN_VALUE;
        long third = Long.MIN_VALUE;
        for (int value : a) {
            // Step 2: Skip a value that we already have. Otherwise put it in the right place and push the others down.
            if (value == first || value == second || value == third) {
                continue;
            }
            if (value > first) {
                third = second;
                second = first;
                first = value;
            } else if (value > second) {
                third = second;
                second = value;
            } else if (value > third) {
                third = value;
            }
        }
        // Step 3: If there is no third value, the answer is the biggest.
        return third == Long.MIN_VALUE ? first : third;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int size = scanner.nextInt();
        int[] a = new int[size];
        for (int i = 0; i < size; i++) {
            a[i] = scanner.nextInt();
        }
        System.out.println(solve(a));
    }
}