Compilare: user.cpp: In function ‘void form_t(std::vector<int, std::allocator<int> >&, std::string)’: user.cpp:12: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:37: warning: comparison between signed and unsigned integer expressions user.cpp:41: warning: comparison between signed and unsigned integer expressions user.cpp:44: warning: comparison between signed and unsigned integer expressions user.cpp:44: warning: comparison between signed and unsigned integer expressions user.cpp:49: warning: comparison between signed and unsigned integer expressions user.cpp:60: warning: comparison between signed and unsigned integer expressions