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

#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define ll long long
#define ull unsigned long long
#define ld long double
#define vl vector<long long>
#define vvl vector<vector<long long>>
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = (s); i < (ll)(n); i++)
#define rrep(i, x) for (ll i = ((ll)(x)-1); i >= 0; i--)
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define vvc vector<vector<char>>
#define vc vector<char>
#define vvb vector<vector<bool>>
#define vb vector<bool>
#define maxe(x) *max_element(all(x))
#define mine(x) *min_element(all(x))
#define Size(x) ((int)(x).size())
#define umap unordered_map
const long long INF = 1LL << 60;
const long double pi = 3.1415926535897932;
long long MOD = 1000000007;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

// lis,modpow,uf,modncr,soinsubunkai,yakusurekkyo,gyakugen
// mint,dijkstra

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n;
  cin >> n;
  ll m = 1000000000000000000;
  ll res = 1;
  bool check = false;
  rep(i, n) {
    ll a;
    cin >> a;
    if (a == 0) {
      cout << 0 << endl;
      return 0;
    }
    if (a > m / res) {
      res = 1;
      check = true;
    } else {
      res *= a;
    }
  }
  if (check) {
    cout << -1 << endl;
  } else {
    cout << res << endl;
  }
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define ll long long
#define ull unsigned long long
#define ld long double
#define vl vector<long long>
#define vvl vector<vector<long long>>
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = (s); i < (ll)(n); i++)
#define rrep(i, x) for (ll i = ((ll)(x)-1); i >= 0; i--)
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define vvc vector<vector<char>>
#define vc vector<char>
#define vvb vector<vector<bool>>
#define vb vector<bool>
#define maxe(x) *max_element(all(x))
#define mine(x) *min_element(all(x))
#define Size(x) ((int)(x).size())
#define umap unordered_map
const long long INF = 1LL << 60;
const long double pi = 3.1415926535897932;
long long MOD = 1000000007;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

// lis,modpow,uf,modncr,soinsubunkai,yakusurekkyo,gyakugen
// mint,dijkstra

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n;
  cin >> n;
  ll res = 1;
  bool check = false;
  rep(i, n) {
    ll a;
    cin >> a;
    if (a == 0) {
      cout << 0 << endl;
      return 0;
    }
    if (a > 1000000000000000000 / res) {
      check = true;
    }
    res *= a;
  }
  if (check) {
    cout << -1 << endl;
  } else {
    cout << res << endl;
  }
}