View Compilation Error

2_28141_2115653_29146.cpp:3:1: error: 'string' does not name a type
 string s;
 ^
2_28141_2115653_29146.cpp: In function 'int main()':
2_28141_2115653_29146.cpp:5:11: error: 'cin' was not declared in this scope
     while(cin>>s){
           ^
2_28141_2115653_29146.cpp:5:11: note: suggested alternative:
In file included from 2_28141_2115653_29146.cpp:1:0:
4.9.2/x86_64-w64-mingw32/include/c++/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^
2_28141_2115653_29146.cpp:5:16: error: 's' was not declared in this scope
     while(cin>>s){
                ^
2_28141_2115653_29146.cpp:6:9: error: 'cout' was not declared in this scope
         cout<<s.size()<<endl;
         ^
2_28141_2115653_29146.cpp:6:9: note: suggested alternative:
In file included from 2_28141_2115653_29146.cpp:1:0:
4.9.2/x86_64-w64-mingw32/include/c++/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^
2_28141_2115653_29146.cpp:6:25: error: 'endl' was not declared in this scope
         cout<<s.size()<<endl;
                         ^
2_28141_2115653_29146.cpp:6:25: note: suggested alternative:
In file included from 4.9.2/x86_64-w64-mingw32/include/c++/iostream:39:0,
                 from 2_28141_2115653_29146.cpp:1:
4.9.2/x86_64-w64-mingw32/include/c++/ostream:564:5: note:   'std::endl'
     endl(basic_ostream<_CharT, _Traits>& __os)
     ^