Language: C++

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <cmath>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <tuple>
#include <stack>
#include <bitset>
#include <utility>
#include<iomanip>
// #include <numeric>
using namespace std;



typedef unsigned long ul;
typedef unsigned long long ull;
typedef long long ll;
typedef vector<ll> vint;
typedef vector<vector<ll>> vvint;
typedef vector<string> vstring;
typedef vector<vector<string>> vvstring;
typedef vector<char> vchar;
typedef vector<vector<char>> vvchar;
typedef vector<long double> vdouble;
typedef vector<vector<long double>> vvdouble;
typedef vector<vector<vector<long double>>> vvvdouble;
typedef pair<ll,ll> pint;
typedef vector<pint> vpint;

#define rep(i,n) for(ll i=0;i<n;i++)
#define repf(i,f,n) for(ll i=f;i<n;i++)
#define repr(i,n) for(ll i=n-1;i>=0;i--)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define INT_MAX 2147483647
#define LLONG_MAX 9223372036854775807
#define vmax(vec) *max_element(vec.begin(), vec.end())
#define vmin(vec) *min_element(vec.begin(), vec.end())
#define vsort(vec) sort(vec.begin(), vec.end())
#define vsortgr(vec) sort(vec.begin(), vec.end(), greater<ll>())
#define DIVIDER 1000000007


//
// struct Node{
//   vint children;
//   ll index;
//   ll prop;
// };



int dy[]={0, 0, 1, -1};
int dx[]={1, -1, 0, 0,};

// ll X,Y,Z,K;
// ll pmax = 30000000000;
// vint A,B,C;




// int binary_search(int key){
//  //isOKを満たす要素のうち最小のインデックスを返す。（要ソート）
//   int left = -1;
//   int right = N;
//
//   while(right - left > 1){
//     int mid = left + (right - left)/2;
//
//     if(isOK(mid, key)) right=mid;
//     else left=mid;
//   }
//
//   return right;
// }

// ll gcd(ll m, ll n){
//   if(m<n) swap(m,n);
//   if(n==0) return m;
//   return gcd(n, m%n);
// }

// ll get_pow(ll x, ll y){
//   ll ret=0;
//   ll temp = y;
//   while(true){
//     if(x<=temp) break;
//     ret++;
//     temp *= 2;
//   }
//   return ret;
// }



int main() {
  cout<<fixed<<setprecision(10);

  ll N,M;
  cin>>N>>M;
  vint L(M),R(M);
  rep(i,M)cin>>L[i]>>R[i];

  ll ans = 0;
  ll left = 1;
  ll right = N;

  rep(i,M){
    left = max(left, L[i]);
    right = min(right, R[i]);
  }

  ans = max(right-left+1, 0);

  cout << ans << endl;

}

















//


Compiler output:
a.cc: In function 'int main()':
a.cc:123:12: error: no matching function for call to 'max(ll, int)'
  123 |   ans = max(right-left+1, 0);
      |         ~~~^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 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/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:123:12: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
  123 |   ans = max(right-left+1, 0);
      |         ~~~^~~~~~~~~~~~~~~~~
/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,
                 from a.cc:3:
/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:123:12: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
  123 |   ans = max(right-left+1, 0);
      |         ~~~^~~~~~~~~~~~~~~~~