Language: C++

# include <bits/stdc++.h>
# define rep(i,n) for(int i=0;i<(n);++i)
using namespace sdt;
using ld = long double;
using ll = long long;
int main() {
  int n; cin >> n;
  vector<ld> a(n);
  rep (i, n) cin >> a[i];
  ld prod = 1.0;
  rep (i,n) {
    if (a[i] == 0.0) {
      cout << 0 << endl;
    }
    prod *= a[i];
  }
  ll ans;
  if (prod > 1e18) ans = 0;
  else ans = prod;
  cout << prod << endl;
  return 0;
}

Compiler output:
a.cc:3:17: error: 'sdt' is not a namespace-name
    3 | using namespace sdt;
      |                 ^~~
a.cc: In function 'int main()':
a.cc:7:10: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    7 |   int n; cin >> n;
      |          ^~~
      |          std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:8:3: error: 'vector' was not declared in this scope
    8 |   vector<ld> a(n);
      |   ^~~~~~
a.cc:8:3: note: suggested alternatives:
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:8:12: error: expected primary-expression before '>' token
    8 |   vector<ld> a(n);
      |            ^
a.cc:8:14: error: 'a' was not declared in this scope
    8 |   vector<ld> a(n);
      |              ^
a.cc:13:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   13 |       cout << 0 << endl;
      |       ^~~~
      |       std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:13:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   13 |       cout << 0 << endl;
      |                    ^~~~
      |                    std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:20:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 |   cout << prod << endl;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:20:19: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   20 |   cout << prod << endl;
      |                   ^~~~
      |                   std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~