line1 = gets
abort "line1 return error" unless line1.chomp!
line2 = gets
abort "line2 return error" unless line2.chomp!
abort "line3 error" if gets

na = line1.scan(/^(\d+) (\d+)$/)
abort "line1 format error" if na.empty?
n,a = na[0].map!(&:to_i)

abort "line2 format error" unless /^\d+(?: \d+)*$/=~line2
x = line2.scan(/\d+/).map!(&:to_i)


puts x.inject(:+) == a*n ? "YES" : "NO"