View Compilation Error

0_0_29973417_31127.cpp: In function 'int main()':
0_0_29973417_31127.cpp:9:2: error: 'cin' was not declared in this scope
  cin>>p;
  ^
0_0_29973417_31127.cpp:40:2: error: 'cout' was not declared in this scope
  cout<<setiosflags(ios::fixed)<<setprecision(3)<<sqrt(h)<<endl;//小数位精度需要iomanip 
  ^
0_0_29973417_31127.cpp:40:20: error: incomplete type 'std::ios {aka std::basic_ios<char>}' used in nested name specifier
  cout<<setiosflags(ios::fixed)<<setprecision(3)<<sqrt(h)<<endl;//小数位精度需要iomanip 
                    ^
0_0_29973417_31127.cpp:40:59: error: 'endl' was not declared in this scope
  cout<<setiosflags(ios::fixed)<<setprecision(3)<<sqrt(h)<<endl;//小数位精度需要iomanip 
                                                           ^