题解 | #尼科彻斯定理#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            if (a % 2 == 0) {

                int res  = a * a + 1 - a;
                StringBuffer sb = new StringBuffer(""+res);

                for (int i = 1  ; i < a ; i++ ) {
                    res += 2;
                    sb.append("+" + res);
                }
                System.out.println(sb);

            } else {

                int res = a * a - a + 1;
                StringBuffer sb = new StringBuffer(""+res);
                for (int i = 1  ; i < a ; i++ ) {
                    res += 2;
                    sb.append("+" + res);
                }
                System.out.println(sb);


            }

        }
    }
}