import java.io.PrintWriter
import java.util.*
import kotlin.math.*

fun floorSqrt(n: Long): Long {
    if (n <= 1) return n
    var lo = 1L
    var hi = n
    while (hi - lo > 1) {
        val mid = lo + (hi - lo) / 2
        val sq = mid.toBigInteger().let { it * it }
        if (sq <= n.toBigInteger()) lo = mid
        else hi = mid
    }
    return lo
}

fun primePi(n: Long): Long {
    if (n <= 3) return maxOf(0, n - 1)
    val v = floorSqrt(n).toInt()
    val smalls = (0..v).map { (it + 1) / 2 }.toMutableList()
    var s = (v + 1) / 2
    val roughs = (0 until s).map { 2 * it + 1 }.toMutableList()
    val larges = (0 until s).map { (n / (2 * it + 1) + 1) / 2 }.toMutableList()
    val skip = BooleanArray(v + 1) { false }
    var pc = 0
    for (p in 3..v step 2) {
        if (skip[p]) continue
        val q = p * p.toLong()
        pc++
        if (q * q > n) break
        skip[p] = true
        for (i in q..v step 2L * p) {
            skip[i.toInt()] = true
        }
        var ns = 0
        for (k in 0 until s) {
            val i = roughs[k]
            if (skip[i]) continue
            val d = i * p.toLong()
            val x = if (d <= v) larges[smalls[d.toInt()] - pc] else smalls[(n / d).toInt()].toLong()
            larges[ns] = larges[k] + pc - x
            roughs[ns] = i
            ns++
        }
        s = ns
        var i = v
        for (j in (p..v / p).reversed()) {
            val c = smalls[j] - pc
            val e = j * p.toLong()
            while (i >= e) {
                smalls[i] -= c
                i--
            }
        }
    }
    var res = larges[0] + (s + 2L * (pc - 1)) * (s - 1L) / 2 - larges.slice(1 until s).sum()

    for (l in 1 until s) {
        val q = roughs[l]
        val m = n / q
        val e = smalls[(m / q).toInt()] - pc
        if (e <= l) break
        val t = roughs.slice(l + 1..e).map { smalls[(m / it).toInt()].toLong() }.sum()
        res += t - (e - l) * (pc + l - 1L)
    }
    return res
}

fun PrintWriter.solve() {
    val l = nextLong()
    val r = nextLong()
    println(primePi(r) - primePi(l - 1) + primePi(2 * r) - primePi(2 * l))
}

fun main() {
    val writer = PrintWriter(System.out, false)
    writer.solve()
    writer.flush()
}

// region Scanner
private var st = StringTokenizer("")
private val br = System.`in`.bufferedReader()

fun next(): String {
    while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
    return st.nextToken()
}

fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextLine() = br.readLine()
fun nextDouble() = next().toDouble()
// endregion