Language: C++

#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(vec) vec.begin(), vec.end()
using namespace std;
typedef long long ll;
ll gcd(ll x, ll y){
  return y == 0 ? x : gcd(y, x % y);
}
ll lcg(ll x, ll y){
  return x * y / gcd(x, y);
}
map<ll, ll> factor(ll n){
  map<ll, ll> ans;
  ll a = 2;
  while (n >= a * a){
    if (n % a == 0){
      ans[a]++;
      n /= a;
    }
    else a++;
  }
  ans[n]++;
  return ans;
}

int main(){
  int n; cin >> n;
  vector<int> nums(n);
  rep(i, n) cin >> nums[i];
  int ans = 0;
  rep(i, n){
  	int l = 0, r = 0;
    rep(k, i){
    	l = gcd(l, nums[k]);
    }
    for(int k = i + 1; k < n; k++){
    	r = gcd(r, nums[k]);
    }
    ans = max(ans, gcd(l, r));
  }
  cout << ans << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:56:14: error: no matching function for call to 'max(int&, ll)'
   56 |     ans = max(ans, gcd(l, r));
      |           ~~~^~~~~~~~~~~~~~~~
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:56:14: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'll' {aka 'long long int'})
   56 |     ans = max(ans, gcd(l, r));
      |           ~~~^~~~~~~~~~~~~~~~
/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:4:
/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:56:14: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   56 |     ans = max(ans, gcd(l, r));
      |           ~~~^~~~~~~~~~~~~~~~