print((function (f)
	return f() and "YES" or "NO"
end)((function (M)
	M.cdef 'int scanf(const char *, ...);'
	local C,f = M.C,M.typeof("long[1]")
	local h,w,n,k = f(),f(),f(),f()
	return function ()
		C.scanf("%ld%ld%ld%ld",h,w,n,k)
		local t=h[0]*w[0]
		if t<=n[0] then return t==k[0] end
		if (t%n[0]==k[0]) or (n[0]==k[0] and t%n[0]==0) then return true end
		return false
	end
end)(require'ffi')))