Language: C++

#include <bits/stdc++.h>
using namespace::std;

#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

typedef long long ll;
typedef array<int, 3> tri;
typedef long double ld;

template <class T> istream& operator>>(istream& I, vector<T>& v) {for (T &e: v) I >> e; return I;}
template <class T> ostream& operator<<(ostream &O, const vector<T>& v) {for (const T &e: v) O << e << ' '; return O;}




void _main() {
        int n; cin >> n;
        vector<string> v(n); cin >> v;

        string s;
        for (char c = 'a'; c <= 'z'; c++) {
                int freq = 1e9;
                for (int i = 0; i < n; i++) {
                        freq = min(freq, count(all(v[i]), c));
                }
                s += string(freq, c);
        }


        cout << s;
}




signed main() {
        ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//        freopen("input.txt", "r", stdin);
        int _t = 1;
//        cin >> _t;
        while (_t--) _main();
        return 0;
}


Compiler output:
a.cc: In function 'void _main()':
a.cc:25:35: error: no matching function for call to 'min(int&, std::__iterator_traits<__gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >, void>::difference_type)'
   25 |                         freq = min(freq, count(all(v[i]), c));
      |                                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
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: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:25:35: 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'})
   25 |                         freq = min(freq, count(all(v[i]), c));
      |                                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
/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:
/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:25:35: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   25 |                         freq = min(freq, count(all(v[i]), c));
      |                                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~