Language: C++

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

string part(string str, unsigned int num)
{
	string ret = str.substr(0, 1);
	int count = 0;

	for (unsigned int i = 0; i < str.size() - 1; i++) {
		if (str[i] == 'a' || str[i] == 'i' || str[i] == 'u' || str[i] == 'e' || str[i] == 'o') {
			ret += str.substr(i + 1, 1);
		}
	}

	if (ret.size() > num) {
		ret = ret.substr(0, num);
	}

	return ret;
}

int solve(vector<string>& strings, unsigned int num)
{
	int ans = -1;
	bool flag = true;
	vector<string> parts;

	for (unsigned int i = 0; i < strings.size(); i++) {
		string temp = part(strings[i], num);
		parts.push_back(temp);
	}

	for (unsigned int i = 0; i < parts.size(); i++) {
		for (unsigned int j = i + 1; j < parts.size(); j++) {
			if (parts[i] == parts[j]) {
				flag = false;
				goto End;
			}
		}
	}
End:

	if (flag == true) {
		ans = num;
	}

	return ans;
}

int main()
{
	while (true) {
		int n;
		cin >> n;

		if (n == 0) {
			break;
		}

		vector<string> strings(n);
		unsigned int maxsize = 0;
		for (int i = 0; i < n; i++) {
			cin >> strings[i];
			maxsize = max(maxsize, strings[i].size());
		}

		int ans = -1;
		
		for (unsigned int i = 1; i <= maxsize; i++) {
			ans = solve(strings, i);
			if (ans != -1) {
				break;
			}
		}

		cout << ans << endl;
	}
	
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:67:38: error: no matching function for call to 'max(unsigned int&, std::__cxx11::basic_string<char>::size_type)'
   67 |                         maxsize = max(maxsize, strings[i].size());
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:67:38: note:   deduced conflicting types for parameter 'const _Tp' ('unsigned int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'})
   67 |                         maxsize = max(maxsize, strings[i].size());
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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:67:38: note:   mismatched types 'std::initializer_list<_Tp>' and 'unsigned int'
   67 |                         maxsize = max(maxsize, strings[i].size());
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~