Eroare de compilare: In file included from /usr/include/c++/4.4/unordered_set:35, from user.cpp:4: /usr/include/c++/4.4/c++0x_warning.h:31:2: error: #error This file requires compiler and library support for the upcoming ISO C++ standard, C++0x. This support is currently experimental, and must be enabled with the -std=c++0x or -std=gnu++0x compiler options. user.cpp: In function ‘int main()’: user.cpp:14: error: ‘unordered_set’ was not declared in this scope user.cpp:14: error: expected primary-expression before ‘>’ token user.cpp:14: error: ‘keys’ was not declared in this scope user.cpp:23: warning: comparison between signed and unsigned integer expressions user.cpp:27: warning: comparison between signed and unsigned integer expressions