Problem p02923 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;

#define fastio                                                                 \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);

#define ll long long
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define mp make_pair
#define pu push
#define pp pop_back
#define in insert
#define ld long double
#define forn(low, high, i) for (i = low; i < high; i++)
#define forrev(high, low, i) for (i = high; i >= low; i--)
#define trace(x) cerr << #x << ": " << x << " " << endl;
#define all(v) v.begin(), v.end()
#define sz(v) (int)v.size()
#define line cout << __LINE__;
#define prv(a)                                                                 \
  for (auto x : a)                                                             \
    cout << x << ' ';                                                          \
  cout << '\n';
#define decimal_digits cout << fixed << setprecision(15);
#define dbg2(a, b) cerr << #a << " = " << a << " " << #b << " = " << b << '\n';
#define debug(x) cerr << __LINE__ << ' ' << #x << " = " << x << '\n';
#define dln cerr << '\n';
#define dsp cerr << ' ';
#define pln cout << '\n';
#define psp cout << ' ';

typedef unordered_map<int, int> umi;
typedef unordered_map<ll, ll> uml;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const int inf = 1e9;
const ll INF = 1e18;
const ll mod = 1e9 + 7;

inline ll add(ll a, ll b) { return ((a % mod) + (b % mod)) % mod; }
inline ll sub(ll a, ll b) { return ((a % mod) - (b % mod) + mod) % mod; }
inline ll mul(ll a, ll b) { return ((a % mod) * (b % mod)) % mod; }
inline ll modexpo(ll a, ll b) {
  ll res = 1;
  while (b) {
    if (b & 1) {
      res = mul(res, a);
    }
    a = mul(a, a);
    b /= 2;
  }
  return res;
}
inline ll divide(ll a, ll b) { return mul(a, modexpo(b, mod - 2)); }

clock_t time_p = clock();

void ktj() {
  time_p = clock() - time_p;
  cerr << "Time elapsed : " << (float)(time_p) / CLOCKS_PER_SEC << "\n";
}

int main() {
  fastio

      ll n,
      i, j, k, ans = 0;
  cin >> n;
  ll a[n];
  forn(0, n, i) { cin >> a[i]; }

  forn(0, n, i) {
    ll now = 0;
    forn(i + 1, n, j) {
      if (a[j] > a[j - 1])
        break;
    }
    ll len = j - i;
    ans = max(ans, len);
  }

  cout << ans - 1 << '\n';

  ktj();
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;

#define fastio                                                                 \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);

#define ll long long
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define mp make_pair
#define pu push
#define pp pop_back
#define in insert
#define ld long double
#define forn(low, high, i) for (i = low; i < high; i++)
#define forrev(high, low, i) for (i = high; i >= low; i--)
#define trace(x) cerr << #x << ": " << x << " " << endl;
#define all(v) v.begin(), v.end()
#define sz(v) (int)v.size()
#define line cout << __LINE__;
#define prv(a)                                                                 \
  for (auto x : a)                                                             \
    cout << x << ' ';                                                          \
  cout << '\n';
#define decimal_digits cout << fixed << setprecision(15);
#define dbg2(a, b) cerr << #a << " = " << a << " " << #b << " = " << b << '\n';
#define debug(x) cerr << __LINE__ << ' ' << #x << " = " << x << '\n';
#define dln cerr << '\n';
#define dsp cerr << ' ';
#define pln cout << '\n';
#define psp cout << ' ';

typedef unordered_map<int, int> umi;
typedef unordered_map<ll, ll> uml;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const int inf = 1e9;
const ll INF = 1e18;
const ll mod = 1e9 + 7;

inline ll add(ll a, ll b) { return ((a % mod) + (b % mod)) % mod; }
inline ll sub(ll a, ll b) { return ((a % mod) - (b % mod) + mod) % mod; }
inline ll mul(ll a, ll b) { return ((a % mod) * (b % mod)) % mod; }
inline ll modexpo(ll a, ll b) {
  ll res = 1;
  while (b) {
    if (b & 1) {
      res = mul(res, a);
    }
    a = mul(a, a);
    b /= 2;
  }
  return res;
}
inline ll divide(ll a, ll b) { return mul(a, modexpo(b, mod - 2)); }

clock_t time_p = clock();

void ktj() {
  time_p = clock() - time_p;
  cerr << "Time elapsed : " << (float)(time_p) / CLOCKS_PER_SEC << "\n";
}

int main() {
  fastio

      ll n,
      i, j, k, ans = 0;
  cin >> n;
  ll a[n];
  forn(0, n, i) { cin >> a[i]; }

  forn(0, n, i) {
    ll now = 0;
    forn(i + 1, n, j) {
      if (a[j] > a[j - 1])
        break;
    }
    ll len = j - i;
    ans = max(ans, len);
    i = j - 1;
  }

  cout << ans - 1 << '\n';

  ktj();
}