#pragma region Macros #pragma comment(linker, "/stack:200000000") // #pragma GCC optimize("unroll-loops") // #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,fma,abm,mmx,avx,avx2,tune=native") // #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,fma,abm,mmx,avx,avx2") // #pragma GCC target("avx2") #pragma GCC optimize("Ofast") #include #define ll long long using ld = long double; #define rep2(i, a, b) for(ll i = (a); i <= (b); i++) #define rep3(i, a, b) for(ll i = (a); i >= (b); --i) #define rep(i, n) for(ll i = 0; i < n; ++i) #define pii pair #define pll pair #define pb push_back #define eb emplace_back #define vi vector #define vll vector #define vpi vector #define vpll vector #define overload2(_1, _2, name, ...) name #define vec(type, name, ...) vector name(__VA_ARGS__) #define VEC(type, name, size) \ vector name(size); \ IN(name) #define VEC2(type, name1, name2, size) \ vector name1(size), name2(size); \ for(int i = 0; i < size; i++) IN(name1[i], name2[i]) #define VEC3(type, name1, name2, name3, size) \ vector name1(size), name2(size), name3(size); \ for(int i = 0; i < size; i++) IN(name1[i], name2[i], name3[i]) #define vv(type, name, h, ...) vector> name(h, vector(__VA_ARGS__)) #define VV(type, name, h, w) \ vector> name(h, vector(w)); \ IN(name) #define vvv(type, name, h, w, ...) vector>> name(h, vector>(w, vector(__VA_ARGS__))) #define vvvv(type, name, a, b, c, ...) \ vector>>> name(a, vector>>(b, vector>(c, vector(__VA_ARGS__)))) #define mt make_tuple #define fi first #define se second #define all(c) begin(c), end(c) #define SORT(v) sort(all(v)) #define REV(v) reverse(all(v)) template T SUM(const std::vector &v) { return accumulate(all(v), T(0)); } #define MIN(v) *min_element(all(v)) #define MAX(v) *max_element(all(v)) #define lb(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define ub(c, x) distance((c).begin(), upper_bound(all(c), (x))) using namespace std; constexpr pii dx4[4] = {pii{1, 0}, pii{0, 1}, pii{-1, 0}, pii{0, -1}}; constexpr pii dx8[8] = {{1, 0}, {1, 1}, {0, 1}, {-1, 1}, {-1, 0}, {-1, -1}, {0, -1}, {1, -1}}; const string YESNO[2] = {"NO", "YES"}; const string YesNo[2] = {"No", "Yes"}; const string yesno[2] = {"no", "yes"}; void YES(bool t = 1) { cout << YESNO[t] << endl; } void NO(bool t = 1) { YES(!t); } void Yes(bool t = 1) { cout << YesNo[t] << endl; } void No(bool t = 1) { Yes(!t); } void yes(bool t = 1) { cout << yesno[t] << endl; } void no(bool t = 1) { yes(!t); } template using vc = vector; template using vvc = vector>; template using vvvc = vector>; template using vvvvc = vector>; template using pq = priority_queue; template using pqg = priority_queue, greater>; #define si(c) (int)(c).size() #define INT(...) \ int __VA_ARGS__; \ IN(__VA_ARGS__) #define LL(...) \ ll __VA_ARGS__; \ IN(__VA_ARGS__) #define STR(...) \ string __VA_ARGS__; \ IN(__VA_ARGS__) #define CHR(...) \ char __VA_ARGS__; \ IN(__VA_ARGS__) #define DBL(...) \ double __VA_ARGS__; \ IN(__VA_ARGS__) int scan() { return getchar(); } void scan(int &a) { cin >> a; } void scan(long long &a) { cin >> a; } void scan(char &a) { cin >> a; } void scan(double &a) { cin >> a; } void scan(string &a) { cin >> a; } template void scan(pair &p) { scan(p.first), scan(p.second); } template void scan(vector &); template void scan(vector &a) { for(auto &i : a) scan(i); } template void scan(T &a) { cin >> a; } void IN() {} template void IN(Head &head, Tail &...tail) { scan(head); IN(tail...); } template inline bool chmax(T &a, const S &b) { return (a < b ? a = b, 1 : 0); } template inline bool chmin(T &a, const S &b) { return (a > b ? a = b, 1 : 0); } vi iota(int n) { vi a(n); iota(all(a), 0); return a; } template vi iota(vector &a, bool greater = false) { vi res(a.size()); iota(all(res), 0); sort(all(res), [&](int i, int j) { if(greater) return a[i] > a[j]; return a[i] < a[j]; }); return res; } #define UNIQUE(x) sort(all(x)), x.erase(unique(all(x)), x.end()) template T ceil(T x, T y) { assert(y >= 1); return (x > 0 ? (x + y - 1) / y : x / y); } template T floor(T x, T y) { assert(y >= 1); return (x > 0 ? x / y : (x + y - 1) / y); } template T POW(T x, int n) { T res = 1; for(; n; n >>= 1, x *= x) if(n & 1) res *= x; return res; } template T POW(T x, ll n, const ll &mod) { T res = 1; for(; n; n >>= 1, x = x * x % mod) if(n & 1) res = res * x % mod; return res; } vector factor(ll x) { vector ans; for(ll i = 2; i * i <= x; i++) if(x % i == 0) { ans.push_back({i, 1}); while((x /= i) % i == 0) ans.back().second++; } if(x != 1) ans.push_back({x, 1}); return ans; } template vector divisor(T x) { vector ans; for(T i = 1; i * i <= x; i++) if(x % i == 0) { ans.pb(i); if(i * i != x) ans.pb(x / i); } return ans; } template void zip(vector &x) { vector y = x; UNIQUE(y); for(int i = 0; i < x.size(); ++i) { x[i] = lb(y, x[i]); } } template void fold_in(vector &v) {} template void fold_in(vector &v, Head &&a, Tail &&...tail) { for(auto e : a) v.emplace_back(e); fold_in(v, tail...); } template void renumber(vector &v) {} template void renumber(vector &v, Head &&a, Tail &&...tail) { for(auto &&e : a) e = lb(v, e); renumber(v, tail...); } template vector zip(vector &head, Args &&...args) { vector v; fold_in(v, head, args...); sort(all(v)), v.erase(unique(all(v)), v.end()); renumber(v, head, args...); return v; } // x in [l, r) template bool inc(const T &x, const S &l, const S &r) { return l <= x and x < r; } // (a, b) in [lx, rx) * [ly, ry) template bool inc(const pair &x, const S &lx, const S &ly, const S &rx, const S &ry) { return inc(x.fi, lx, rx) && inc(x.se, ly, ry); } constexpr ll ten(int n) { return n == 0 ? 1 : ten(n - 1) * 10; } // bit 演算系 ll pow2(int i) { return 1LL << i; } int topbit(signed t) { return t == 0 ? -1 : 31 - __builtin_clz(t); } int topbit(ll t) { return t == 0 ? -1 : 63 - __builtin_clzll(t); } int lowbit(signed a) { return a == 0 ? 32 : __builtin_ctz(a); } int lowbit(ll a) { return a == 0 ? 64 : __builtin_ctzll(a); } // int allbit(int n) { return (1 << n) - 1; } ll allbit(ll n) { return (1LL << n) - 1; } int popcount(signed t) { return __builtin_popcount(t); } int popcount(ll t) { return __builtin_popcountll(t); } bool ispow2(int i) { return i && (i & -i) == i; } ll rnd(ll l, ll r) { //[l, r] #ifdef _LOCAL static mt19937_64 gen; #else static mt19937_64 gen(chrono::steady_clock::now().time_since_epoch().count()); #endif return uniform_int_distribution(l, r)(gen); } template void random_shuffle(vc &a) { rep(i, si(a)) swap(a[i], a[rnd(0, i)]); } int in() { int x; cin >> x; return x; } ll lin() { unsigned long long x; cin >> x; return x; } template pair operator-(const pair &x, const pair &y) { return pair(x.fi - y.fi, x.se - y.se); } template pair operator+(const pair &x, const pair &y) { return pair(x.fi + y.fi, x.se + y.se); } template pair operator&(const pair &l, const pair &r) { return pair(max(l.fi, r.fi), min(l.se, r.se)); } template pair operator+=(pair &l, const pair &r) { return l = l + r; } template pair operator-=(pair &l, const pair &r) { return l = l - r; } template ll operator*(const pair &x, const pair &y) { return (ll)x.fi * y.fi + (ll)x.se * y.se; } template struct edge { int from, to; T cost; int id; edge(int to, T cost) : from(-1), to(to), cost(cost) {} edge(int from, int to, T cost) : from(from), to(to), cost(cost) {} edge(int from, int to, T cost, int id) : from(from), to(to), cost(cost), id(id) {} constexpr bool operator<(const edge &rhs) const noexcept { return cost < rhs.cost; } edge &operator=(const int &x) { to = x; return *this; } operator int() const { return to; } }; template using Edges = vector>; using Tree = vector>; using Graph = vector>; template using Wgraph = vector>>; Graph getG(int n, int m = -1, bool directed = false, int margin = 1) { Tree res(n); if(m == -1) m = n - 1; while(m--) { int a, b; cin >> a >> b; a -= margin, b -= margin; res[a].emplace_back(b); if(!directed) res[b].emplace_back(a); } return res; } template Wgraph getWg(int n, int m = -1, bool directed = false, int margin = 1) { Wgraph res(n); if(m == -1) m = n - 1; while(m--) { int a, b; T c; cin >> a >> b >> c; a -= margin, b -= margin; res[a].emplace_back(b, c); if(!directed) res[b].emplace_back(a, c); } return res; } void add(Graph &G, int x, int y) { G[x].eb(y), G[y].eb(x); } template void add(Wgraph &G, int x, int y, S c) { G[x].eb(y, c), G[y].eb(x, c); } #define i128 __int128_t #define ull unsigned long long int #define TEST \ INT(testcases); \ while(testcases--) template ostream &operator<<(ostream &os, const vector &v) { for(auto it = begin(v); it != end(v); ++it) { if(it == begin(v)) os << *it; else os << " " << *it; } return os; } template ostream &operator<<(ostream &os, const pair &p) { os << p.first << " " << p.second; return os; } template string to_string(pair p) { return "(" + to_string(p.first) + "," + to_string(p.second) + ")"; } string to_string(string s) { return "\"" + s + "\""; } string to_string(char c) { return string(1, c); } template string to_string(vector s) { string res = "{"; for(auto it = s.begin(); it != s.end(); it++) res += to_string(*it) + (next(it) == s.end() ? "" : ", "); return res + "}"; } template string to_string(set s) { string res = "{"; for(auto it = s.begin(); it != s.end(); it++) res += to_string(*it), res += (next(it) == end(s) ? "" : ", "); return res + "}"; } #define endl '\n' #ifdef _LOCAL void dump() { cerr << endl; } template void dump(Head head, Tail... tail) { cerr << to_string(head) << " "; dump(tail...); } #undef endl #define debug(x) \ cout << #x << ": "; \ dump(x) #else void dump() {} template void dump(Head head, Tail... tail) {} #define debug(x) #endif template void print(const T &a) { cout << a; } void OUT() { cout << endl; } template void OUT(const Head &head, const Tail &...tail) { print(head); if(sizeof...(tail)) cout << ' '; OUT(tail...); } template static constexpr T inf = numeric_limits::max() / 2; struct Setup_io { Setup_io() { ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0); cout << fixed << setprecision(15); } } setup_io; #define drop(s) cout << #s << endl, exit(0) template struct ndFORarray { std::array v; ndFORarray(std::array v_) : v(v_) {} struct ndFORitr { const std::array &v; std::array tmp; bool is_end; ndFORitr(const std::array &v_) : v(v_), tmp(), is_end(false) {} bool operator!=(const ndFORitr &) const { return !is_end; } void operator++() { int pos = N - 1; while(pos != -1) { tmp[pos] += 1; if(tmp[pos] == v[pos]) { tmp[pos] = 0; pos -= 1; } else { break; } } if(pos == -1) { is_end = true; } } const std::array &operator*() const { return tmp; } }; ndFORitr begin() const { return ndFORitr(v); } ndFORitr end() const { return ndFORitr(v); } }; struct ndFORvector { std::vector v; ndFORvector(std::vector v_) : v(v_) {} struct ndFORitr { const std::vector &v; std::vector tmp; bool is_end; ndFORitr(const std::vector &v_) : v(v_), tmp(v.size(), 0), is_end(false) {} bool operator!=(const ndFORitr &) const { return !is_end; } void operator++() { int pos = v.size() - 1; while(pos != -1) { tmp[pos] += 1; if(tmp[pos] == v[pos]) { tmp[pos] = 0; pos -= 1; } else { break; } } if(pos == -1) { is_end = true; } } const std::vector &operator*() const { return tmp; } }; ndFORitr begin() const { return ndFORitr(v); } ndFORitr end() const { return ndFORitr(v); } }; auto ndFOR(std::vector v) { return ndFORvector(v); } template auto ndFOR(Ts... v) { return ndFORarray>::value>({v...}); } template struct REC { F f; REC(F &&f_) : f(std::forward(f_)) {} template auto operator()(Args &&...args) const { return f(*this, std::forward(args)...); } }; template vector> runLength(const vector &v) { vector> res; for(auto &e : v) { if(res.empty() or res.back().fi != e) res.eb(e, 1); else res.back().se++; } return res; } vector> runLength(const string &v) { vector> res; for(auto &e : v) { if(res.empty() or res.back().fi != e) res.eb(e, 1); else res.back().se++; } return res; } template T bin_search(T ok, T ng, const F &f) { while(abs(ok - ng) > 1) { T mid = ok + ng >> 1; (f(mid) ? ok : ng) = mid; } return ok; } #pragma endregion // https://judge.yosupo.jp/submission/23126 namespace inner { using i32 = int32_t; using u32 = uint32_t; using i64 = int64_t; using u64 = uint64_t; template T gcd(T a, T b) { while(b) swap(a %= b, b); return a; } uint64_t gcd_impl(uint64_t n, uint64_t m) { constexpr uint64_t K = 5; for(int i = 0; i < 80; ++i) { uint64_t t = n - m; uint64_t s = n - m * K; bool q = t < m; bool p = t < m * K; n = q ? m : t; m = q ? t : m; if(m == 0) return n; n = p ? n : s; } return gcd_impl(m, n % m); } uint64_t gcd_pre(uint64_t n, uint64_t m) { for(int i = 0; i < 4; ++i) { uint64_t t = n - m; bool q = t < m; n = q ? m : t; m = q ? t : m; if(m == 0) return n; } return gcd_impl(n, m); } uint64_t gcd_fast(uint64_t n, uint64_t m) { return n > m ? gcd_pre(n, m) : gcd_pre(m, n); } template T inv(T a, T p) { T b = p, x = 1, y = 0; while(a) { T q = b % a; swap(a, b /= a); swap(x, y -= q * x); } assert(b == 1); return y < 0 ? y + p : y; } template T modpow(T a, U n, T p) { T ret = 1; for(; n; n >>= 1, a = U(a) * a % p) if(n & 1) ret = U(ret) * a % p; return ret; } } // namespace inner using namespace std; unsigned long long rng() { static unsigned long long x_ = 88172645463325252ULL; x_ = x_ ^ (x_ << 7); return x_ = x_ ^ (x_ >> 9); } using namespace std; struct ArbitraryLazyMontgomeryModInt { using mint = ArbitraryLazyMontgomeryModInt; using i32 = int32_t; using u32 = uint32_t; using u64 = uint64_t; static u32 mod; static u32 r; static u32 n2; static u32 get_r() { u32 ret = mod; for(i32 i = 0; i < 4; ++i) ret *= 2 - mod * ret; return ret; } static void set_mod(u32 m) { assert(m < (1 << 30)); assert((m & 1) == 1); mod = m; n2 = -u64(m) % m; r = get_r(); assert(r * mod == 1); } u32 a; ArbitraryLazyMontgomeryModInt() : a(0) {} ArbitraryLazyMontgomeryModInt(const int64_t &b) : a(reduce(u64(b % mod + mod) * n2)){}; static u32 reduce(const u64 &b) { return (b + u64(u32(b) * u32(-r)) * mod) >> 32; } mint &operator+=(const mint &b) { if(i32(a += b.a - 2 * mod) < 0) a += 2 * mod; return *this; } mint &operator-=(const mint &b) { if(i32(a -= b.a) < 0) a += 2 * mod; return *this; } mint &operator*=(const mint &b) { a = reduce(u64(a) * b.a); return *this; } mint &operator/=(const mint &b) { *this *= b.inverse(); return *this; } mint operator+(const mint &b) const { return mint(*this) += b; } mint operator-(const mint &b) const { return mint(*this) -= b; } mint operator*(const mint &b) const { return mint(*this) *= b; } mint operator/(const mint &b) const { return mint(*this) /= b; } bool operator==(const mint &b) const { return (a >= mod ? a - mod : a) == (b.a >= mod ? b.a - mod : b.a); } bool operator!=(const mint &b) const { return (a >= mod ? a - mod : a) != (b.a >= mod ? b.a - mod : b.a); } mint operator-() const { return mint() - mint(*this); } mint pow(u64 n) const { mint ret(1), mul(*this); while(n > 0) { if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const mint &b) { return os << b.get(); } friend istream &operator>>(istream &is, mint &b) { int64_t t; is >> t; b = ArbitraryLazyMontgomeryModInt(t); return (is); } mint inverse() const { return pow(mod - 2); } u32 get() const { u32 ret = reduce(a); return ret >= mod ? ret - mod : ret; } static u32 get_mod() { return mod; } }; typename ArbitraryLazyMontgomeryModInt::u32 ArbitraryLazyMontgomeryModInt::mod; typename ArbitraryLazyMontgomeryModInt::u32 ArbitraryLazyMontgomeryModInt::r; typename ArbitraryLazyMontgomeryModInt::u32 ArbitraryLazyMontgomeryModInt::n2; using namespace std; struct montgomery64 { using mint = montgomery64; using i64 = int64_t; using u64 = uint64_t; using u128 = __uint128_t; static u64 mod; static u64 r; static u64 n2; static u64 get_r() { u64 ret = mod; for(i64 i = 0; i < 5; ++i) ret *= 2 - mod * ret; return ret; } static void set_mod(u64 m) { assert(m < (1LL << 62)); assert((m & 1) == 1); mod = m; n2 = -u128(m) % m; r = get_r(); assert(r * mod == 1); } u64 a; montgomery64() : a(0) {} montgomery64(const int64_t &b) : a(reduce((u128(b) + mod) * n2)){}; static u64 reduce(const u128 &b) { return (b + u128(u64(b) * u64(-r)) * mod) >> 64; } mint &operator+=(const mint &b) { if(i64(a += b.a - 2 * mod) < 0) a += 2 * mod; return *this; } mint &operator-=(const mint &b) { if(i64(a -= b.a) < 0) a += 2 * mod; return *this; } mint &operator*=(const mint &b) { a = reduce(u128(a) * b.a); return *this; } mint &operator/=(const mint &b) { *this *= b.inverse(); return *this; } mint operator+(const mint &b) const { return mint(*this) += b; } mint operator-(const mint &b) const { return mint(*this) -= b; } mint operator*(const mint &b) const { return mint(*this) *= b; } mint operator/(const mint &b) const { return mint(*this) /= b; } bool operator==(const mint &b) const { return (a >= mod ? a - mod : a) == (b.a >= mod ? b.a - mod : b.a); } bool operator!=(const mint &b) const { return (a >= mod ? a - mod : a) != (b.a >= mod ? b.a - mod : b.a); } mint operator-() const { return mint() - mint(*this); } mint pow(u128 n) const { mint ret(1), mul(*this); while(n > 0) { if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const mint &b) { return os << b.get(); } friend istream &operator>>(istream &is, mint &b) { int64_t t; is >> t; b = montgomery64(t); return (is); } mint inverse() const { return pow(mod - 2); } u64 get() const { u64 ret = reduce(a); return ret >= mod ? ret - mod : ret; } static u64 get_mod() { return mod; } }; typename montgomery64::u64 montgomery64::mod, montgomery64::r, montgomery64::n2; namespace fast_factorize { using u64 = uint64_t; template bool miller_rabin(u64 n, vector as) { if(mint::get_mod() != n) mint::set_mod(n); u64 d = n - 1; while(~d & 1) d >>= 1; mint e{1}, rev{int64_t(n - 1)}; for(u64 a : as) { if(n <= a) break; u64 t = d; mint y = mint(a).pow(t); while(t != n - 1 && y != e && y != rev) { y *= y; t *= 2; } if(y != rev && t % 2 == 0) return false; } return true; } bool is_prime(u64 n) { if(~n & 1) return n == 2; if(n <= 1) return false; if(n < (1LL << 30)) return miller_rabin(n, {2, 7, 61}); else return miller_rabin(n, {2, 325, 9375, 28178, 450775, 9780504, 1795265022}); } template T pollard_rho(T n) { if(~n & 1) return 2; if(is_prime(n)) return n; if(mint::get_mod() != n) mint::set_mod(n); mint R, one = 1; auto f = [&](mint x) { return x * x + R; }; auto rnd = [&]() { return rng() % (n - 2) + 2; }; while(1) { mint x, y, ys, q = one; R = rnd(), y = rnd(); T g = 1; constexpr int m = 128; for(int r = 1; g == 1; r <<= 1) { x = y; for(int i = 0; i < r; ++i) y = f(y); for(int k = 0; g == 1 && k < r; k += m) { ys = y; for(int i = 0; i < m && i < r - k; ++i) q *= x - (y = f(y)); g = inner::gcd_fast(q.get(), n); } } if(g == n) do g = inner::gcd_fast((x - (ys = f(ys))).get(), n); while(g == 1); if(g != n) return g; } exit(1); } vector inner_factorize(u64 n) { if(n <= 1) return {}; u64 p; if(n <= (1LL << 30)) p = pollard_rho(n); else p = pollard_rho(n); if(p == n) return {p}; auto l = inner_factorize(p); auto r = inner_factorize(n / p); copy(begin(r), end(r), back_inserter(l)); return l; } vector factorize(u64 n) { auto ret = inner_factorize(n); sort(begin(ret), end(ret)); return ret; } } // namespace fast_factorize using fast_factorize::factorize; using fast_factorize::is_prime; int main() { LL(l, r); // (a + b) * (b - a + 1) / 2 ll ans = 0; rep2(i, l, r - 1) { if(is_prime(i * 2 + 1)) ans++; } rep2(i, l, r) if(is_prime(i)) ans++; OUT(ans); }