Language: C++

#include <iostream>
using namespace std;

int main() {
	#include <iostream>
#include <vector>
using namespace std;
 
int main() {
	int n,m;
	cin >> n >> m;
	int l=0,r=1e9;
	for (int i=0; i<m; i++){
		int x,y;
		cin >> x >> y;
		if (l<x) l=x;
		if (r>y) r=y;
	}
	if (r-l<0) cout << 0;
	else out << r-l+1;
	return 0;
}
	return 0;
}

Compiler output:
In file included from /usr/include/c++/14/bits/requires_hosted.h:31,
                 from /usr/include/c++/14/iostream:38,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_uninitialized.h: In function 'int main()':
/usr/include/c++/14/bits/stl_uninitialized.h:70:15: error: expected '=' before '__attribute__'
   70 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_uninitialized.h:70:15: error: expected identifier before '__attribute__'
In file included from /usr/include/c++/14/vector:65,
                 from a.cc:6:
/usr/include/c++/14/bits/stl_uninitialized.h:70:14: error: expected ';' before '__attribute__'
   70 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/bits/stl_uninitialized.h:71:1: error: expected primary-expression before '{' token
   71 | {
      | ^
/usr/include/c++/14/bits/stl_vector.h:77:15: error: expected '=' before '__attribute__'
   77 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:77:15: error: expected identifier before '__attribute__'
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:77:14: error: expected ';' before '__attribute__'
   77 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/bits/stl_vector.h:78:1: error: expected primary-expression before '{' token
   78 | {
      | ^
/usr/include/c++/14/bits/stl_bvector.h:68:15: error: expected '=' before '__attribute__'
   68 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_bvector.h:68:15: error: expected identifier before '__attribute__'
In file included from /usr/include/c++/14/vector:67:
/usr/include/c++/14/bits/stl_bvector.h:68:14: error: expected ';' before '__attribute__'
   68 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/bits/stl_bvector.h:69:1: error: expected primary-expression before '{' token
   69 | {
      | ^
/usr/include/c++/14/bits/vector.tcc:59:15: error: expected '=' before '__attribute__'
   59 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:59:15: error: expected identifier before '__attribute__'
In file included from /usr/include/c++/14/vector:72:
/usr/include/c++/14/bits/vector.tcc:59:14: error: expected ';' before '__attribute__'
   59 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/bits/vector.tcc:60:1: error: expected primary-expression before '{' token
   60 | {
      | ^
/usr/include/c++/14/bits/vector.tcc:1218:15: error: expected '=' before '__attribute__'
 1218 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:1218:15: error: expected identifier before '__attribute__'
/usr/include/c++/14/bits/vector.tcc:1218:14: error: expected ';' before '__attribute__'
 1218 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/bits/vector.tcc:1219:1: error: expected primary-expression before '{' token
 1219 | {
      | ^
/usr/include/c++/14/vector:88:15: error: expected '=' before '__attribute__'
   88 | namespace std _GLIBCXX_VISIBILITY(default)
      |               ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/vector:88:15: error: expected identifier before '__attribute__'
/usr/include/c++/14/vector:88:14: error: expected ';' before '__attribute__'
   88 | namespace std _GLIBCXX_VISIBILITY(default)
      |              ^
      |              ;
/usr/include/c++/14/vector:89:1: error: expected primary-expression before '{' token
   89 | {
      | ^
a.cc:9:9: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
    9 | int main() {
      |         ^~
a.cc:9:9: note: remove parentheses to default-initialize a variable
    9 | int main() {
      |         ^~
      |         --
a.cc:9:9: note: or replace parentheses with braces to value-initialize a variable
a.cc:9:12: error: a function-definition is not allowed here before '{' token
    9 | int main() {
      |            ^