class UnionFind(val size: Int) {
    private val vec = IntArray(size){-1}
    fun find(a: Int): Int {
        return if (vec[a] < 0) {
            a
        }else {
            vec[a] = find(vec[a])
            vec[a]
        }
    }
    fun same(a: Int, b: Int): Boolean {
        return find(a) == find(b)
    }
    fun unite(a: Int, b: Int): Boolean {
        val ar = find(a)
        val br = find(b)
        if (ar == br) return false
        if (vec[ar] < vec[br]) {
            vec[ar] += vec[br]
            vec[br] = ar
        }else {
            vec[br] += vec[ar]
            vec[ar] = br
        }
        return true
    }
    fun sizeOf(a: Int): Int {
        return -vec[find(a)]
    }
}

fun main() {
    val (left, right) = readLine()!!.trim().split(' ').map(String::toInt)
    val uft = UnionFind(right - left + 1)
    var cost = 0
    outer@for (rest in 0 .. right) {
        for (i in left .. right) {
            for (j in i + rest .. right step i) {
                if (uft.unite(i - left, j - left)) {
                    cost += rest
                    if (uft.sizeOf(0) == uft.size) {
                        break@outer
                    }
                }
            }
        }
    }
    println(cost)
}