1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
#include <bits/stdc++.h>

using namespace std;

#define ll long long

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;

typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;

typedef pair<int,int> ii;

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

const int MOD = 998244353;

ll read(){
    ll i;
    cin>>i;
    return i;
}

vi readvi(int n,int off=0,int shift=0){
    vi v(n+shift);
    rep(i,shift)v[i]=0;
    rep(i,n)v[i+shift]=read()+off;
    return v;
}

void YesNo(bool condition, bool do_exit=true) {
    if (condition)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
    if (do_exit)
        exit(0);
}

int main(void ) {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    vi a = readvi(n);

    vi len(n);
    vi rmax(n);

    vi stos;
    stos.push_back(2e6);

    int rm = a[n-1];
    for (int i = n-1; i >= 0; i--) {
        while (stos.back() <= a[i])
            stos.pop_back();
        len[i] = stos.size();
        rm = max(rm, a[i]);
        rmax[i] = rm;
        stos.push_back(a[i]);
    }

    vi first_larger(2e6,-1);

    int mx = -1;

    rep(i,n) {
        rng(x,mx,a[i])
            first_larger[x] = i;
        mx = max(mx, a[i]);
    }

    int res = 0;
    rep(i,n) {
        int act = len[i] + (first_larger[rmax[i]] >= 0 ? len[first_larger[rmax[i]]] : 0);
        res = max(res, act);
    }

    cout << res << endl;

    return 0;
}