class UnionFind: def __init__(self, n): self.n = n self.parents = [-1] * n self.group = n def find(self, x): if self.parents[x] < 0: return x else: self.parents[x] = self.find(self.parents[x]) return self.parents[x] def union(self, x, y): x = self.find(x) y = self.find(y) if x == y: return self.group -= 1 if self.parents[x] > self.parents[y]: x, y = y, x self.parents[x] += self.parents[y] self.parents[y] = x def size(self, x): return -self.parents[self.find(x)] def same(self, x, y): return self.find(x) == self.find(y) def members(self, x): root = self.find(x) return [i for i in range(self.n) if self.find(i) == root] def roots(self): return [i for i, x in enumerate(self.parents) if x < 0] def group_count(self): return self.group def all_group_members(self): dic = {r:[] for r in self.roots()} for i in range(self.n): dic[self.find(i)].append(i) return dic def __str__(self): return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots()) l, r = map(int, input().split()) UF = UnionFind(r - l + 1) for i in range(l, r + 1): div = [] for j in range(1, int(i ** 0.5 + 1)): if i % j == 0: if l <= j <= r: div.append(j) j = i // j if l <= j <= r: div.append(j) d0 = div[0] for d in div[1:]: UF.union(d0 - l, d - l) print(UF.group_count() - 1)