This lets you choose r items from a list of n items (n Choose r). Separate numbers in list by space or comma e.g 1 2 3 or 1,2,3 or -1,0,1. Enter ranges using a colon or hyphen e.g. 1-100 or -10:10. Negative numbers are also allowed. ASCII ranges and symbols are also allowed e.g. a-z, A-Z, 0-z, !-z, !-~, etc.