Main.cc:2:1: error: ‘sing’ does not name a type; did you mean ‘uint’? sing namespace std; ^~~~ uint Main.cc: In function ‘int main()’: Main.cc:4:5: error: ‘cout’ was not declared in this scope cout<<"5050"; ^~~~ Main.cc:4:5: note: suggested alternative: In file included from Main.cc:1:0: /usr/include/c++/7/iostream:61:18: note: ‘std::cout’ extern ostream cout; /// Linked to standard output ^~~~