Trouble Installing ROS Melodic Morenia on Linux Mint 19.1 Tessa [closed]

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Hey there, i'm having trouble installing ROS Melodic on my laptop which runs Linux Mint 19.1 Tessa, below are the output i get when i tried to sudo apt update,

Hit:1 http://ppa.launchpad.net/gerardpuig/ppa/ubuntu bionic InRelease          
Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease                        
Ign:3 http://packages.linuxmint.com tessa InRelease                            
Get:4 http://security.ubuntu.com/ubuntu bionic-security InRelease [88,7 kB]    
Ign:5 http://packages.ros.org/ros/ubuntu tessa InRelease                       
Get:6 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88,7 kB]      
Hit:7 http://packages.linuxmint.com tessa Release                              
Hit:8 http://archive.canonical.com/ubuntu bionic InRelease                     
Err:9 http://packages.ros.org/ros/ubuntu tessa Release                         
  404  Not Found [IP: 64.50.236.52 80]
Get:11 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74,6 kB]
Reading package lists... Done                                
E: The repository 'http://packages.ros.org/ros/ubuntu tessa Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

and here is the output when i tried sudo apt install ros-melodic-desktop

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package ros-melodic-desktop

before that i've done this,

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'

and this,

sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116

just like in the tutorials on ROS wiki

any help would be appreciated.