def f(t,t2,l,r,arr)
	tz=Rational(0,1)
	if l==r then
		t3=arr[l]-t2-t
		p t3
		if tz<=t3 then
			return l
		else
			return l+1
		end
	end
	m=(l+r)/2
	t3=arr[m]-t2
	p [0,l,r,m,t,t3]
	if t3<=tz then
		return f(t,t2,l,m,arr)
	end
	t3=t3-t
	p [t,t3]
	if t3<tz then
		return f(t,t2,l,m,arr)
	else
		return f(t,t2,m+1,r,arr)
	end
end
n,p,q=gets.split(" ").map{|e| e.to_i}
t=Rational(p, q+p)
tA=[0]
tB=[0]
tAB=[0]
n.times{|i|
	a,b=gets.split(" ").map{|e| e.to_i}
	tA<<tA[i]+a
	tB<<tB[i]+b
	tAB<<tAB[i]+a+b
}
arr=[]
(1..n).each{|i|
	arr<<Rational(tA[i],tAB[i])
}
arr=arr.sort.reverse
ans=0
n.times{|i|
	t2=Rational(0,1)
	if i>0 then
		t2=Rational(tA[i],tAB[i])
	end
	p f(t,t2,0,n-1,arr)
}
puts ans

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

MyAxIDMKMSA0CjIgOAo3IDI=

3 1 3
1 4
2 8
7 2