Language: C++

#include<bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using ull = unsigned long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;

long long gcd(long long a, long long b) {
    if (b == 0) return a;
    else return gcd(b, a % b);
}

int main() {
  int n;
  cin >> n;
  vector<int> A(n);
  rep(i, n) cin >> A[i];
  if (n == 2) {
    cout << max(A[0], A[1]) << endl;;
    return 0;
  }
  ll a = gcd(A[0], A[1]);
  rep(i, n) a = gcd(a, A[i]);
  rep(i, n) A[i] /= a;
  ll b = gcd(A[0], A[1]);
  b = max(b, gcd(A[0], A[2]));
  b = max(b, gcd(A[1], A[2]));
  bool skiped = false;
  rep(i, n) {
    int tmp = gcd(b, A[i]);
    if (tmp == 1 && !skiped) {
      skiped = true;
    } else {
      b = tmp;
    }
  }
  int ans = a * b;
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:27:10: error: no matching function for call to 'max(ll&, std::common_type_t<int, int>)'
   27 |   b = max(b, gcd(A[0], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~
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:27:10: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'std::common_type_t<int, int>' {aka 'int'})
   27 |   b = max(b, gcd(A[0], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~
/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:27:10: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   27 |   b = max(b, gcd(A[0], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~
a.cc:28:10: error: no matching function for call to 'max(ll&, std::common_type_t<int, int>)'
   28 |   b = max(b, gcd(A[1], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~
/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:28:10: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'std::common_type_t<int, int>' {aka 'int'})
   28 |   b = max(b, gcd(A[1], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~
/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
/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:28:10: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   28 |   b = max(b, gcd(A[1], A[2]));
      |       ~~~^~~~~~~~~~~~~~~~~~~~