Language: C++

#include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG
#define rep(i,n) for(int i=0; i<(n); i++)
#define all(n) begin(n),end(n)
using ll = long long;
using P = pair<int,int>;

int main() {
    int n, m;
    cin >> n >> m;
    ll lmx = 1, rmn = n;
    rep(i,m) {
        int l, r;
        cin >> l >> r;
        lmx = max(lmx, l);
        rmn = min(rmn, r);
    } 
    ll ans = rmn - lmx + 1;
    cout << ans << endl;

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:18: error: no matching function for call to 'max(ll&, int&)'
   16 |         lmx = max(lmx, l);
      |               ~~~^~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:16:18: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
   16 |         lmx = max(lmx, l);
      |               ~~~^~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:16:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   16 |         lmx = max(lmx, l);
      |               ~~~^~~~~~~~
a.cc:17:18: error: no matching function for call to 'min(ll&, int&)'
   17 |         rmn = min(rmn, r);
      |               ~~~^~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)'
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note:   template argument deduction/substitution failed:
a.cc:17:18: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
   17 |         rmn = min(rmn, r);
      |               ~~~^~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)'
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5686:5: note: candidate: 'template<class _Tp> constexpr _Tp std::min(initializer_list<_Tp>)'
 5686 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5686:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::min(initializer_list<_Tp>, _Compare)'
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note:   template argument deduction/substitution failed:
a.cc:17:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   17 |         rmn = min(rmn, r);
      |               ~~~^~~~~~~~