a,b=gets.split.map{|e| e.to_i}
n=gets.to_i
x=gets.split.map{|e| Rational(e,1)}
a=Rational(a*1000,3600)
b=Rational(b*1000,3600)
ok="YES"
(n-1).times{|i|
	t=x[i]/a*b
	ok="NO" if x[i+1]<t
}
puts ok