require 'prime'
m,n,*c=$<.read.split.map &:to_i
d=[-1]*m<<0
m.downto(1){|i|c.each{|j|d[i-j]=[d[i-j],d[i]+1].max if d[i]>=0&&j<=i}}
p d.max+0.upto(m).inject{|p,c|p+(c.prime?&&d[c]>0?d[c]:0)}