Language: C++

#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<climits>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<bitset>
#include<iomanip>
using namespace std;

#define rep(i,j,n) for(int i=(j);i<(n);i++)
#define rep2(i,j,n) for(int i=(j);i<=(n);i++)
#define all(i) i.begin(),i.end()
#define INF 1e9

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef pair<int, int> pi;
typedef long long i64;

int main() {
	int n;
	cin >> n;
	vi cou(26, INF);
	rep(i, 0, n) {
		string s;
		cin >> s;
		rep(j, 0, 26) {
			cou[j] = min(cou[j], count(all(s), 'a' + j));
		}
	}
	string ans;
	rep(i, 0, 26) {
		char x = 'a' + i;
		rep(j, 0, cou[i]) {
			ans += x;
		}
	}
	cout << ans << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:35:37: error: no matching function for call to 'min(__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type&, std::__iterator_traits<__gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >, void>::difference_type)'
   35 |                         cou[j] = min(cou[j], count(all(s), 'a' + j));
      |                                  ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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: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:35:37: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'std::__iterator_traits<__gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >, void>::difference_type' {aka 'long int'})
   35 |                         cou[j] = min(cou[j], count(all(s), 'a' + j));
      |                                  ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/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:35:37: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   35 |                         cou[j] = min(cou[j], count(all(s), 'a' + j));
      |                                  ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~