#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
int dp[2000][2000], pos[2000];
bool above(pi a, pi b, pi c) {
b.f -= a.f, b.s -= a.s;
c.f -= a.f, c.s -= a.s;
return (ll)c.s*b.f-(ll)c.f*b.s >= 0;
}
int get(int l, int r) {
if (l > r) return 0;
return dp[l][r];
}
void ad(int x, int y) {
pos[x] = y;
dp[x][x] = 1;
int sum = 1, bes = x;
vi cur = {x};
F0Rd(i,x) {
dp[i][x] = dp[i][x-1];
if (above({i,pos[i]},{bes,pos[bes]},{x,pos[x]})) {
bes = i;
sum += get(i+1,cur.back()-1);
cur.pb(i);
}
dp[i][x] = max(dp[i][x],sum+get(i,cur.back()-1));
}
}
int maximum_deevs(vi v) {
F0R(i,sz(v)) ad(i,v[i]);
return dp[0][sz(v)-1];
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cout << maximum_deevs({1,2,3,4,5,6});
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
Compilation message
/tmp/ccj2g1Og.o: In function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/ccYr6XEc.o:mountains.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
