Caffe2 c++ api doesn't work on Ubuntu

Hello, I need to run these tutorials. I installed PyTorch on Ubuntu 16 with the instructions in this book and it works well with Python, but when I test it in c++ (Caffe2 C++ api), it prints that:

root@baki:~/caffe2_cpp_tutorial/build# cmake ..
../caffe2: warning: directory does not exist.
CMake Error at CMakeLists.txt:36 (message):
  Caffe2 lib not found

-- Configuring incomplete, errors occurred!

What can I do?