830. 单调栈

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

public class Main{
     static Stack<Integer> sta=new Stack<>();
     public static void main(String[] args) {
            Scanner scan=new Scanner(System.in);
            int m=scan.nextInt();
            while(m-->0){
                    int num=scan.nextInt();
                    while(!sta.isEmpty() && sta.peek()>=num) sta.pop();
                    if(sta.isEmpty()) System.out.print("-1 ");
                    else System.out.print(sta.peek()+" ");
                    sta.push(num);
            }
    }
}