f_in = File::open("data3.txt", "r")
out = File::open("out3.txt", "w")
while (!f_in.eof?)
    num = f_in.gets.strip.to_i
    t = 0
    # build up
    while (t < num)
        t = t + 1
        out << "*"*t + "\n"
    end
    # build down
    t = num - 1
    while (t > 0)
        out << "*"*t + "\n"
        t = t - 1
    end
    
end
f_in.close
out.close