Language: C++

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

int main(){
    int n, m;
    cin >> n >> m;
    int count = 0;
    int cityCount = n;
    vector<vector<int>> path(m, vector<int>(2));
    for(int i = 0;i < m;i++){
        cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
    }
    sort(path.begin(), path.end());
    vector<int> pBit(n);
    for(int i = 0;i < m;i++){
        if(pBit.at(path.at(i).at(0)) == 0){
            count++;
            pBit.at(path.at(i).at(0)) = count;
            cityCount--;
        }
        if(pBit.at(path.at(i).at(1)) == 0){
            cityCount--;
            pBit.at(path.at(i).at(1)) = count;
        }
        else{
            for(int j = 0;j < m;j++){
                if(pBit.at(path.at(j).at(1)) == pBit.at(path.at(i).at(1))){
                    pBit.at(path.at(j).at(1)) = count;
                }
            }

        }
    }
    cout << cityCount + count - 1 << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:13: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'})
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |         ~~~ ^~ ~~~~~~~~~~~~~~~~~~~~
      |         |                       |
      |         |                       __gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type {aka int}
      |         std::istream {aka std::basic_istream<char>}
In file included 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,
                 from a.cc:1:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'int&' to an rvalue of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'long long unsigned int&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:219:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'float&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:223:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'double&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:227:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  227 |       operator>>(long double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:227:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: cannot bind non-const lvalue reference of type 'long double&' to a value of type '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'}
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:11:33: error: invalid conversion from '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} to 'void*' [-fpermissive]
   11 |         cin >> path.at(i).at(0) - 1 >> path.at(i).at(1) - 1;
      |                ~~~~~~~~~~~~~~~~~^~~
      |                                 |
      |                                 __gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type {aka int}
a.cc:11:33: e