Language: C++

#include <bits/stdc++.h>
int main(){
  int N;
  cin >> N;
  vector<int> H(N);
  for(int i=0; i < N; i++){
    cin >> H.at(i);
  }
  for(int i=0; i < N; i++){
    if(H.at(i)-H.at(i+1) > 2){
      cout << "No" << endl;
      break;
    }
    else if(H.at(i)-H.at(i+1)==1&&H.at(i+1)-H.at(i+2)){
      cout << "No" << endl;
      break;
    }
    else if(i=N-1){
      cout << "Yes" << endl;
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:4:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    4 |   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:5:3: error: 'vector' was not declared in this scope
    5 |   vector<int> H(N);
      |   ^~~~~~
a.cc:5:3: 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:5:10: error: expected primary-expression before 'int'
    5 |   vector<int> H(N);
      |          ^~~
a.cc:7:12: error: 'H' was not declared in this scope
    7 |     cin >> H.at(i);
      |            ^
a.cc:10:8: error: 'H' was not declared in this scope
   10 |     if(H.at(i)-H.at(i+1) > 2){
      |        ^
a.cc:11:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   11 |       cout << "No" << 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:11:23: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   11 |       cout << "No" << 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:15:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   15 |       cout << "No" << 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:15:23: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   15 |       cout << "No" << endl;
      |                       ^~~~
      |                       std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:19:7: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   19 |       cout << "Yes" << 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:19:24: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   19 |       cout << "Yes" << endl;
      |                        ^~~~
      |                        std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~