usage:
("X", "Y", and "Z" is int)
XdY: throw X Y-side dice(s).
YcX: choose X number(s) from 1 to Y.
XsY: get the sum of X Y-side dice(s).
XsYxZ: get the sum of X Y-side dice(s) for Z times.
add "z" in front or back of the command to print the outcome in one line.
input "q" or "quit" to exit.