Compilare: user.cpp: In function ‘int main()’: user.cpp:18:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(2); i < s.size(); i++) { ~~^~~~~~~~~~ user.cpp:12:9: warning: unused variable ‘l’ [-Wunused-variable] int l = s.size(); ^ user.cpp:8:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("password.in", "r", stdin); ^ user.cpp:9:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("password.out", "w", stdout); ^