Main.cc:3:17: error: ‘tsd’ is not a namespace-name using namespace tsd; ^~~ Main.cc:3:20: error: expected namespace-name before ‘;’ token using namespace tsd; ^ Main.cc: In function ‘int main()’: Main.cc:6:2: error: ‘cin’ was not declared in this scope cin>>n; ^~~ Main.cc:6:2: note: suggested alternative: In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:75:0, from Main.cc:1: /usr/include/c++/7/iostream:60:18: note: ‘std::cin’ extern istream cin; /// Linked to standard input ^~~ Main.cc:8:8: error: ‘a’ was not declared in this scope cin>>a[i]; ^ Main.cc:10:7: error: ‘a’ was not declared in this scope sort(a + 1,a + n + 1); ^ Main.cc:10:2: error: ‘sort’ was not declared in this scope sort(a + 1,a + n + 1); ^~~~ Main.cc:10:2: note: suggested alternative: In file included from /usr/include/c++/7/algorithm:62:0, from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:65, from Main.cc:1: /usr/include/c++/7/bits/stl_algo.h:4856:5: note: ‘std::sort’ sort(_RandomAccessIterator __first, _RandomAccessIterator __last, ^~~~ Main.cc:12:3: error: ‘cout’ was not declared in this scope cout<