get the list of file names
declare a hash for output
open the first file
while reading each line from the file
    get the first column of the line for use as a hash key
    assign the line as the value of hash element using that key

for each remaining file
    open the file
    while reading each line from the file
        get the first column of the line for use as a hash key
        append the line to the current value of the hash element using that key

for each key in the hash
     print the value of the hash element using that key