x, y = gets.split.map(&:to_i)
n = gets.to_i
a = gets.split.map(&:to_i)
x = Rational(5 * x, 18)
y = Rational(5 * y, 18)
ans = []
(0...n-1).each do |i|
  ans << (Rational(a[i], x) <= Rational(a[i+1], y) ? true : false)
end
puts ans.all?{|b| b == true} ? 'YES' : 'NO'