Compilare: user.cpp: In function ‘void test()’: user.cpp:69:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < ans[i].size(); ++ j) ^ user.cpp:70:61: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] cout << ans[i][j] << " \n"[j + 1 == ans[i].size()]; ^ user.cpp: In function ‘int main()’: user.cpp:75:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rgb.in", "r", stdin); ^ user.cpp:76:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rgb.out", "w", stdout); ^