Programming: Write a program to encrypt$/$decrypt any numerical file. Use shitting by $3$ as an encryption method. Your code should have an encryption method and a decryption method. For testing, generate a matrix of size $1010$ of random numbers between $100-1000$ as an input file. Your running screen should accept command lines such as:

enc $-$in filename $-$out en$-$filename

dec $-$in filename $-$out de$-$filename