simple php script

hello i need the following 2 small php scripts: scrip1, please let me know if you can do this with 1 gig or not: i want a simple page where the user will select 2 .txt files from his pc. lets say file1 and file2 the file1 will have all the numbers(one per line), e.g. 6974527983 6974111983 6974527983 6974527111 6971111113 file2 will have the following number, e.g. 6974111983 6974527111 so a file3 will be generated with the numbers that are not within the file2 but exists in file1, so the file3 will be: 6974527983 6974527983 6971111113 of counrse i will apply this to large ammount of numbers, e.g. 10.000 numbers so it must be nice and fast and also another question for a quiet same project. lets say that i have a txt file with 10.000 numbers (one number per line) i want to be able to select this file and automatically to all the number, in every line at the begining to be put a number of my choice so the interface will be like 1) select your txt file 2) which number to put at the begining so lets assume that i select my file and i also write the number 30, so if my file has the following numbers inside: 6974444777 6974444776 6974444775 another file, called file2 must be generated with the following numbers inside: 306974444777 306974444776 306974444775