11722.cpp

#include <stdio.h>
#include <vector>
#include <algorithm>

using namespace std;

int N, answer;
vector<int> arr, dp;
int dfs(int now)
{
    if (dp[now] != 0)
        return dp[now];
    int re = 0;
    for (int i = now + 1; i < N; i++)
    {
        if (arr[now] > arr[i])
        {
            re = max(re, dfs(i));
        }
    }
    answer = max(answer, dp[now] = max(dp[now], re + 1));
    return re + 1;
}
int main()
{
    scanf("%d", &N);
    arr.assign(N, 0);
    dp.assign(N, 0);
    for (int i = 0; i < N; i++)
    {
        scanf("%d", &arr[i]);
    }

    for (int i = 0; i < N; i++)
    {
        dfs(i);
    }

    printf("%d\n", answer);
    return 0;
}