if true then
  fh=STDIN
else
  fh=open("in0100.txt")
end

while fh.gets do
  s=$_.chomp.split(/=/)
  ans=("0".."9").to_a.select do |x|
    s0=s[0].gsub(/X/,x)
    s1=s[1].gsub(/X/,x)
    s0 !~ /^0/ and s1 !~ /^0/ and eval(s0)==eval(s1)
  end
  puts (ans.length==0) ? "NA" : ans
end