L, R = map(int, input().split())

S = list(range(L, R + 1))


class UnionFind:
    def __init__(self, N):  # 頂点数 N
        self.table = [i for i in range(N)]    # 親 table[x] == x で根
        self.rank = [1 for i in range(N)]    # 木の長さ
        self.size = [1 for i in range(N)]    # 集合のサイズ

    def Find(self, x):  # xの根を返す
        if self.table[x] == x:
            return x
        else:
            self.table[x] = self.Find(self.table[x])  # 親の更新
            self.size[x] = self.size[self.table[x]]
            return self.table[x]

    def Unite(self, x, y):
        x, y = self.Find(x), self.Find(y)
        sx, sy = self.Size(x), self.Size(y)
        if x == y:
            return
        if self.rank[x] > self.rank[y]:
            self.table[y] = x
            self.size[x] = sx + sy
        else:
            self.table[x] = y
            self.size[y] = sx + sy
            if self.rank[x] == self.rank[y]:
                self.rank[y] += 1

    def Check(self, x, y):
        return self.Find(x) == self.Find(y)

    def Size(self, x):
        return self.size[self.Find(x)]


N = R - L + 1
UF = UnionFind(N)

for s in S:
    n = 2
    while n * s <= R:
        UF.Unite(s - L, n * s - L)
        n += 1

S = set()
for i in range(N):
    S.add(UF.Find(i))

print(len(S) - 1)