Item Get Program

a = {}
a[1] = "redstone"
a[2] = "iron"
a[3] = "tin"
a[4] = "copper"
a[5] = "silver"
a[6] = "gold"
a[7] = "diamond"
a[8] = "redmatter"
a[9] = "darkmatter"
a[10] = "ciruit"
a[11] = "coal"
a[12] = "food"
a[13] = "glasswire"
a[14] = "copperwire"
a[15] = "refinediron"
a[16] = "nikolite"
while true do
 user = ""
 print("-------------------MENU(WIP)-------------------")
 print("1. List")
 print("2. Call")
 user = io.read()
  if user == "1" then
   for i = 1, 16 do
    write(a[i])
    write(", ")
   end
  elseif user == "2" then
   item = ""
   amount = ""
   print("Item:")
   item = io.read()
   print("Amount:")
   amount = io.read()
    for i = 1, 16 do
     if a[i] == item then
      for c = 1, amount do
       rs.setBundledOutput("back", 2^(i-1))
       sleep(0.2)
       rs.setBundledOutput("back", 0)
       sleep(0.2)
      end
      i = 16
     end
    end
    term.clear()
    term.setCursorPos(1, 1)
  else
   write("Not an option")
   term.clear()
   term.setCursorPos(1, 1)
  end
 end