Language: C++

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

const int MOD = 139 + 7;

inline int mul (int a, int b) {
  return (a * 1LL * b) % MOD;
}

int main() {
  int n;
  cin >> n;
  vector<int> cnt(3, 0);
  int ans = 1;
  for (int i = 0; i < n; i++) {
    int a, c = 0, id = -1;
    cin >> a;
    for (int j = 0; j < 3; j++) {
      if (a == cnt[j]) {
        ++c;
        id = j;
      }
    }
    if (id == -1) {
      cout << 0 << endl;
      return 0;
    }
    ans = mul(ans, c);
    ++cnt[id];
  }
  cout << ans << endl;
  return 0;
}


Compiler output:
a.cc:2:7: error: expected nested-name-specifier before 'namesapce'
    2 | using namesapce std;
      |       ^~~~~~~~~
a.cc: In function 'int main()':
a.cc:12:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   12 |   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:13:3: error: 'vector' was not declared in this scope
   13 |   vector<int> cnt(3, 0);
      |   ^~~~~~
a.cc:13:3: 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:13:10: error: expected primary-expression before 'int'
   13 |   vector<int> cnt(3, 0);
      |          ^~~
a.cc:19:16: error: 'cnt' was not declared in this scope; did you mean 'int'?
   19 |       if (a == cnt[j]) {
      |                ^~~
      |                int
a.cc:25:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   25 |       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:25:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   25 |       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:29:7: error: 'cnt' was not declared in this scope; did you mean 'int'?
   29 |     ++cnt[id];
      |       ^~~
      |       int
a.cc:31:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   31 |   cout << ans << 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:31:18: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   31 |   cout << ans << endl;
      |                  ^~~~
      |                  std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~