View Compilation Error

0_0_38339214_28212.cpp:22:57: error: 'operator<<' function uses 'auto' type specifier without trailing return type
 template<class T>auto&operator<<(ostream& os,vector<T>_v){bool a=1;for(auto x:_v){os<<(a?"":" ")<<x;a=0;}return os;}
                                                         ^
0_0_38339214_28212.cpp:22:57: note: deduced return type only available with -std=c++1y or -std=gnu++1y
0_0_38339214_28212.cpp:23:55: error: 'operator<<' function uses 'auto' type specifier without trailing return type
 template<class T>auto &operator<<(ostream& os,set<T>_s){for(auto x:_s){os<<x<<" ";}cout<<endl;return os;}
                                                       ^
0_0_38339214_28212.cpp:23:55: note: deduced return type only available with -std=c++1y or -std=gnu++1y