Great Vova Wall (Version 2)

版权声明：来自星空计算机团队(QQ群：134826825)——申屠志刚 https://blog.csdn.net/weixin_43272781/article/details/85106027

https://codeforces.com/contest/1092/problem/D2

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
//typedef long long ll;
//typedef __int128 lll;
const int N=200000+1000;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,Mx;
int a[N],q[N],h[N],top;
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);Mx=max(Mx,a[i]);
        q[++top]=a[i];
        if(top>1&&q[top]==q[top-1]){
            if(q[top]<h[top-1]) continue;
            top-=2,h[top]=q[top+1];
            h[top+1]=0; h[top+2]=0;
        }
    }
    if(top==0||(top==1&&q[top]==Mx)) puts("YES");
    else puts("NO");

    //cout << "Hello world!" << endl;
    return 0;
}