print((function (f)
	return f(io.stdin) and "YES" or "NO"
end)(function (fh)
	local x,y,n,a,b=fh:read("*n"),fh:read("*n"),fh:read("*n"),fh:read("*n"),0
	for i=2,n do b=fh:read("*n") if a*y>b*x then return false end a=b end
	return true
end))