View Compilation Error

0_0_37649354_17728.cpp:19:1: error: 'string' does not name a type
 string s;
 ^
0_0_37649354_17728.cpp:21:16: error: 'string' was not declared in this scope
 int insertTree(string s)
                ^
0_0_37649354_17728.cpp:21:16: note: suggested alternative:
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/iosfwd:39:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ios:38,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ostream:38,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/iostream:39,
                 from 0_0_37649354_17728.cpp:1:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stringfwd.h:62:33: note:   'std::string'
   typedef basic_string<char>    string;   
                                 ^
0_0_37649354_17728.cpp:22:1: error: expected ',' or ';' before '{' token
 {
 ^