[백준] 1874번 스택 수열

import java.util.Scanner;
import java.util.Stack;

public class Main {
    public static void main(String[] args) {
    	
    	Scanner kb = new Scanner(System.in);
    	StringBuilder sb = new StringBuilder(); 
    	Stack<Integer> stack = new Stack<>();
    	
    	int n = kb.nextInt();
    	int start = 1;


    	for(int i = 0; i < n; i++) {
    		int input = kb.nextInt();

    		while (start <= input) {
    			stack.push(start);
    			sb.append("+\n"); 
    			start++;
    		}

    		if (stack.peek() == input) {
    			stack.pop();
    			sb.append("-\n"); 
    		} else {
    			System.out.println("NO");
    			return;
    		}
    	}

    	System.out.println(sb.toString());
    }
}