Compilare: main.cpp: In member function 'bool Expression::tryPerm(Expression::Sum)': main.cpp:35:13: warning: unused variable 'i' [-Wunused-variable] int i(0) ; ^ main.cpp:36:13: warning: unused variable 'special' [-Wunused-variable] int special(0) ; ^~~~~~~ main.cpp: In member function 'void Expression::add(std::__cxx11::string, bool)': main.cpp:66:26: warning: array subscript has type 'char' [-Wchar-subscripts] notzero[ss[0]] = true; ^ main.cpp: In member function 'void Expression::bkt(int)': main.cpp:81:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (p + 1 == lett.size()) { ~~~~~~^~~~~~~~~~~~~~ main.cpp: In member function 'int Expression::solutions()': main.cpp:105:13: warning: unused variable 'ret' [-Wunused-variable] int ret(0) ; ^~~ main.cpp: In member function 'bool Expression::debug()': main.cpp:136:5: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'int main()': main.cpp:141:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("artifact.in", "r", stdin) ; ^ main.cpp:142:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("artifact.out", "w", stdout) ; ^