Problem p02658 (C++) — buggy submission, verdict: Runtime Error

#pragma GCC optimize("O3")

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

#define ll long long
#define ld long double
#define rep(i, n) for (ll i = 0; i < n; ++i)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define vi vector<int>
#define vll vector<ll>
#define vpi vector<pii>
#define vpll vector<pll>

#define Size(c) (int)(c).size()
#define INT(...)                                                               \\
  int __VA_ARGS__;                                                             \\
  IN(__VA_ARGS__)
#define LL(...)                                                                \\
  ll __VA_ARGS__;                                                              \\
  IN(__VA_ARGS__)
#define ULL(...)                                                               \\
  ull __VA_ARGS__;                                                             \\
  IN(__VA_ARGS__)
#define STR(...)                                                               \\
  string __VA_ARGS__;                                                          \\
  IN(__VA_ARGS__)
#define CHR(...)                                                               \\
  char __VA_ARGS__;                                                            \\
  IN(__VA_ARGS__)
#define DBL(...)                                                               \\
  double __VA_ARGS__;                                                          \\
  IN(__VA_ARGS__)
#define LD(...)                                                                \\
  ld __VA_ARGS__;                                                              \\
  IN(__VA_ARGS__)

int scan() { return getchar(); }
void scan(int &a) { cin >> a; }
void scan(long long &a) { cin >> a; }
void scan(char &a) { cin >> a; }
void scan(double &a) { cin >> a; }
void scan(long double &a) { cin >> a; }
void scan(char a[]) { scanf("%s", a); }
void scan(string &a) { cin >> a; }
template <class T> void scan(vector<T> &);
template <class T, size_t size> void scan(array<T, size> &);
template <class T, class L> void scan(pair<T, L> &);
template <class T, size_t size> void scan(T (&)[size]);
template <class T> void scan(vector<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T> void scan(deque<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, size_t size> void scan(array<T, size> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, class L> void scan(pair<T, L> &p) {
  scan(p.first);
  scan(p.second);
}
template <class T, size_t size> void scan(T (&a)[size]) {
  for (auto &i : a)
    scan(i);
}
template <class T> void scan(T &a) { cin >> a; }

void IN() {}
template <class Head, class... Tail> void IN(Head &head, Tail &...tail) {
  scan(head);
  IN(tail...);
}

#define ios cin.tie(NULL), ios_base::sync_with_stdio(false)
#define cfs(n) cout << fixed << setprecision((n))
#define endl '\\n'
#define ret return 0

constexpr ll mod = 998244353;
constexpr ll mod2 = 10e9 + 7;
const double PI = 3.1415926535897932384626433832795028841971; // acos(-1)

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
// endmacro

ll a[100010];
int main() {
  ios;
  cfs(15);

  INT(n);
  rep(i, n) {
    scan(a[i]);
    if (a[i] == 0) {
      cout << "0" << endl;
      ret;
    }
  }

  ll prod = 1;
  rep(i, n) {
    if (a[i] <= 1000000000000000000 / prod) {
      prod *= a[i];
    } else {
      prod = -1;
      break;
    }
  }

  cout << prod << endl;
  ret;
}


Error: WA

Fixed submission:

#pragma GCC optimize("O3")

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

#define ll long long
#define ld long double
#define rep(i, n) for (ll i = 0; i < n; ++i)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define vi vector<int>
#define vll vector<ll>
#define vpi vector<pii>
#define vpll vector<pll>

#define Size(c) (int)(c).size()
#define INT(...)                                                               \\
  int __VA_ARGS__;                                                             \\
  IN(__VA_ARGS__)
#define LL(...)                                                                \\
  ll __VA_ARGS__;                                                              \\
  IN(__VA_ARGS__)
#define ULL(...)                                                               \\
  ull __VA_ARGS__;                                                             \\
  IN(__VA_ARGS__)
#define STR(...)                                                               \\
  string __VA_ARGS__;                                                          \\
  IN(__VA_ARGS__)
#define CHR(...)                                                               \\
  char __VA_ARGS__;                                                            \\
  IN(__VA_ARGS__)
#define DBL(...)                                                               \\
  double __VA_ARGS__;                                                          \\
  IN(__VA_ARGS__)
#define LD(...)                                                                \\
  ld __VA_ARGS__;                                                              \\
  IN(__VA_ARGS__)

int scan() { return getchar(); }
void scan(int &a) { cin >> a; }
void scan(long long &a) { cin >> a; }
void scan(char &a) { cin >> a; }
void scan(double &a) { cin >> a; }
void scan(long double &a) { cin >> a; }
void scan(char a[]) { scanf("%s", a); }
void scan(string &a) { cin >> a; }
template <class T> void scan(vector<T> &);
template <class T, size_t size> void scan(array<T, size> &);
template <class T, class L> void scan(pair<T, L> &);
template <class T, size_t size> void scan(T (&)[size]);
template <class T> void scan(vector<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T> void scan(deque<T> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, size_t size> void scan(array<T, size> &a) {
  for (auto &i : a)
    scan(i);
}
template <class T, class L> void scan(pair<T, L> &p) {
  scan(p.first);
  scan(p.second);
}
template <class T, size_t size> void scan(T (&a)[size]) {
  for (auto &i : a)
    scan(i);
}
template <class T> void scan(T &a) { cin >> a; }

void IN() {}
template <class Head, class... Tail> void IN(Head &head, Tail &...tail) {
  scan(head);
  IN(tail...);
}

#define ios cin.tie(NULL), ios_base::sync_with_stdio(false)
#define cfs(n) cout << fixed << setprecision((n))
#define endl '\\n'
#define ret return 0

constexpr ll mod = 998244353;
constexpr ll mod2 = 10e9 + 7;
const double PI = 3.1415926535897932384626433832795028841971; // acos(-1)

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
// endmacro

ll a[100010];
int main() {
  ios;
  cfs(15);

  INT(n);
  rep(i, n) {
    LL(a[i]);
    if (a[i] == 0) {
      cout << "0" << endl;
      ret;
    }
  }

  ll prod = 1;
  rep(i, n) {
    if (a[i] <= 1000000000000000000 / prod) {
      prod *= a[i];
    } else {
      prod = -1;
      break;
    }
  }

  cout << prod << endl;
  ret;
}