Problem p02759 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")

#include <bits/stdc++.h>
#include <iostream>
using namespace std;

typedef long long int ll;
typedef long double ld;
typedef unsigned long long ull;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;

#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define tr(x, container) for (auto &x : container)
#define fr(i, n) for (ll i = 0; i < (n); ++i)
#define frs(i, s, n) for (ll i = s; i < (n); ++i)
#define frb(i, s, e) for (ll i = s; i <= (e); ++i)
#define rfr(i, n) for (ll i = (n - 1); i >= 0; i--)
#define frbr(i, e, s) for (ll i = e; i >= (s); i--)
#define mset(m, v) memset(m, v, sizeof(m))
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define find_bug(x) cout << '>' << #x << " : " << x << endl;

void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}
#ifndef ONLINE_JUDGE
#define dbg(x...)                                                              \
  cerr << "[" << #x << "] = [";                                                \
  _print(x)
#define dbg_arr(a, n)                                                          \
  cerr << "[" << #a << "] = [ ";                                               \
  fr(i, n) cerr << a[i] << " ";                                                \
  cerr << "]\n";
#define dbg_mat(m, r, c)                                                       \
  cerr << "[" << #m << "]:\n";                                                 \
  fr(i, r) {                                                                   \
    cerr << "[ ";                                                              \
    fr(j, c) cerr << m[i][j] << " ";                                           \
    cerr << "]\n";                                                             \
  }
#define dbg_time(t) cerr << "Time elapsed: " << t << endl;
#else
#define dbg(x...)                                                              \
  {}
#define dbg_arr(a, n)                                                          \
  {}
#define dbg_mat(m, r, c)                                                       \
  {}
#define dbg_time(t)                                                            \
  {}
#endif

const ll MOD = 1e9 + 7;
const ll SMOD = 998244353;
const ll INF = 1e18;
const ll SINF = 1e9;
const ll MAX = 100100;

/*******************************************************************************************************************/

void pre() {}

void solve() {
  ll n;
  cin >> n;
  if (n % 2 == 0)
    cout << n / 2 << '\n';
  else {
    cout << (n + 1) / 2 << '\n';
  }
}

signed main() {
  clock_t begin = clock();
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif

  // cout<<fixed<<setprecision(15);
  // pre();

  ll test = 1;
  // cin>>test;
  fr(ii, test) {
    // cout << "Case #" << ii + 1 << ": "<<endl;
    solve();
  }

  clock_t end = clock();
  double elapsed_secs = (double)(end - begin) / CLOCKS_PER_SEC;
  dbg_time(elapsed_secs);

  return 0;
}


Fixed submission:
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")

#include <bits/stdc++.h>
#include <iostream>
using namespace std;

typedef long long int ll;
typedef long double ld;
typedef unsigned long long ull;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;

#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define tr(x, container) for (auto &x : container)
#define fr(i, n) for (ll i = 0; i < (n); ++i)
#define frs(i, s, n) for (ll i = s; i < (n); ++i)
#define frb(i, s, e) for (ll i = s; i <= (e); ++i)
#define rfr(i, n) for (ll i = (n - 1); i >= 0; i--)
#define frbr(i, e, s) for (ll i = e; i >= (s); i--)
#define mset(m, v) memset(m, v, sizeof(m))
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define find_bug(x) cout << '>' << #x << " : " << x << endl;

void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}
#ifndef ONLINE_JUDGE
#define dbg(x...)                                                              \
  cerr << "[" << #x << "] = [";                                                \
  _print(x)
#define dbg_arr(a, n)                                                          \
  cerr << "[" << #a << "] = [ ";                                               \
  fr(i, n) cerr << a[i] << " ";                                                \
  cerr << "]\n";
#define dbg_mat(m, r, c)                                                       \
  cerr << "[" << #m << "]:\n";                                                 \
  fr(i, r) {                                                                   \
    cerr << "[ ";                                                              \
    fr(j, c) cerr << m[i][j] << " ";                                           \
    cerr << "]\n";                                                             \
  }
#define dbg_time(t) cerr << "Time elapsed: " << t << endl;
#else
#define dbg(x...)                                                              \
  {}
#define dbg_arr(a, n)                                                          \
  {}
#define dbg_mat(m, r, c)                                                       \
  {}
#define dbg_time(t)                                                            \
  {}
#endif

const ll MOD = 1e9 + 7;
const ll SMOD = 998244353;
const ll INF = 1e18;
const ll SINF = 1e9;
const ll MAX = 100100;

/*******************************************************************************************************************/

void pre() {}

void solve() {
  ll n;
  cin >> n;
  if (n % 2 == 0)
    cout << n / 2 << '\n';
  else {
    cout << (n + 1) / 2 << '\n';
  }
}

signed main() {
  clock_t begin = clock();
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

  // cout<<fixed<<setprecision(15);
  // pre();

  ll test = 1;
  // cin>>test;
  fr(ii, test) {
    // cout << "Case #" << ii + 1 << ": "<<endl;
    solve();
  }

  clock_t end = clock();
  double elapsed_secs = (double)(end - begin) / CLOCKS_PER_SEC;
  dbg_time(elapsed_secs);

  return 0;
}