Language: C++

#include<iostream>
using namespace std;

int main(void){
	int w,n,x,y,temp;
	int a[31];
	char c;
	string str;
	istringstream is(str);
	for(int i = 0; i < 31; i++){
		a[i] = i;
	}
	scanf("%d %d",&w,&n);
	for(int i = 0; i < n; i++){
		getline(str,7);
		is >> x >> c >> y;
		temp = a[x];
		a[x] = a[y];
		a[y] = temp;
	}

	for(int i = 0; i < w; i++){
		cout << a[i + 1] << endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:29: error: variable 'std::istringstream is' has initializer but incomplete type
    9 |         istringstream is(str);
      |                             ^
a.cc:15:24: error: no matching function for call to 'getline(std::string&, int)'
   15 |                 getline(str,7);
      |                 ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/string:55,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.tcc:907:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
  907 |     getline(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:907:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:4117:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4117 |     getline(basic_istream<_CharT, _Traits>& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4117:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   15 |                 getline(str,7);
      |                 ~~~~~~~^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4125:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 4125 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4125:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/basic_string.h:4132:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::getline(basic_istream<_CharT, _Traits>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 4132 |     getline(basic_istream<_CharT, _Traits>&& __is,
      |     ^~~~~~~
/usr/include/c++/14/bits/basic_string.h:4132:5: note:   template argument deduction/substitution failed:
a.cc:15:24: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   15 |                 getline(str,7);
      |                 ~~~~~~~^~~~~~~
In file included from /usr/include/c++/14/cstdio:42,
                 from /usr/include/c++/14/ext/string_conversions.h:45,
                 from /usr/include/c++/14/bits/basic_string.h:4154:
/usr/include/stdio.h:697:18: note: candidate: '__ssize_t getline(char**, size_t*, FILE*)'
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                  ^~~~~~~
/usr/include/stdio.h:697:18: note:   candidate expects 3 arguments, 2 provided