ROS Kinetic on Raspbian Stretch E:Unable to locate package ros-kinetic-freenect-launch E:Unable to locate package ros-kinetic-depthimage-to-laserscan

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I am planning to work on using the Kinect for map building and obstacle avoidance. I have installed ROS-Kinetic successfully by following this ROS wiki installation. I am following this installation guide to install Kinect with ROS Kinetic. When I try these commands:

sudo apt install ros-kinetic-freenect-launch 
sudo apt install ros-kinetic-depthimage-to-laserscan

I get the following error:

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package ros-kinetic-depthimage-to-laserscan

Reading package lists... Done
Building dependency tree
Reading state information... Done
E:Unable to locate package ros-kinetic-freenect-launch

Can someone help me solve the issue?