Compilare: user.cpp: In function ‘void Solve(std::string)’: user.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.size(); ++i) { ^ user.cpp:13:9: warning: unused variable ‘want’ [-Wunused-variable] int want = n / 2; ^ user.cpp: In function ‘int main()’: user.cpp:57:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets.in", "r", stdin); ^ user.cpp:58:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets.out", "w", stdout); ^