Main.cc: In function ‘int main()’: Main.cc:12:23: error: no match for ‘operator=’ (operand types are ‘std::basic_ostream::__ostream_type {aka std::basic_ostream}’ and ‘long long int’) cout<& std::basic_ostream<_CharT, _Traits>::operator=(std::basic_ostream<_CharT, _Traits>&&) [with _CharT = char; _Traits = std::char_traits] operator=(basic_ostream&& __rhs) ^~~~~~~~ /usr/include/c++/7/ostream:402:7: note: no known conversion for argument 1 from ‘long long int’ to ‘std::basic_ostream&&’