Main.cc:3:7: error: expected nested-name-specifier before ‘namepace’ using namepace std; ^~~~~~~~ Main.cc: In function ‘int main()’: Main.cc:6:5: error: ‘string’ was not declared in this scope string s; ^~~~~~ Main.cc:6:5: note: suggested alternatives: In file included from /usr/include/c++/7/iosfwd:39:0, from /usr/include/c++/7/ios:38, from /usr/include/c++/7/ostream:38, from /usr/include/c++/7/iostream:39, from Main.cc:1: /usr/include/c++/7/bits/stringfwd.h:74:33: note: ‘std::__cxx11::string’ typedef basic_string string; ^~~~~~ /usr/include/c++/7/bits/stringfwd.h:74:33: note: ‘std::__cxx11::string’ Main.cc:7:5: error: ‘cin’ was not declared in this scope cin >> s; ^~~ Main.cc:7:5: note: suggested alternative: In file included from Main.cc:1:0: /usr/include/c++/7/iostream:60:18: note: ‘std::cin’ extern istream cin; /// Linked to standard input ^~~ Main.cc:7:12: error: ‘s’ was not declared in this scope cin >> s; ^ Main.cc:8:18: error: ‘cout’ was not declared in this scope if (s == "") cout << 1; ^~~~ Main.cc:8:18: 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 ^~~~ Main.cc:9:23: error: ‘cout’ was not declared in this scope else if (s == "") cout << 1; ^~~~ Main.cc:9:23: 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 ^~~~ Main.cc:10:23: error: ‘cout’ was not declared in this scope else if (s == "") cout << 1; ^~~~ Main.cc:10:23: 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 ^~~~ Main.cc:11:23: error: ‘cout’ was not declared in this scope else if (s == "") cout << 1; ^~~~ Main.cc:11:23: 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 ^~~~ Main.cc:12:23: error: ‘cout’ was not declared in this scope else if (s == "") cout << 1; ^~~~ Main.cc:12:23: 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 ^~~~