#include // #include // #include // #include // #include using namespace std; using ll = long long; using VI = vector; using VL = vector; using VD = vector; using VS = vector; using VB = vector; using VVB = vector>; using VVI = vector; using VVL = vector; using VVD = vector; using PII = std::pair; using VPII = std::vector>; using PLL = std::pair; using VPLL = std::vector>; using TI3 = std::tuple; using TI4 = std::tuple; using TL3 = std::tuple; using TL4 = std::tuple; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--) #define rep2(i, s, n) for (int i = (s); i < (int)(n); i++) #define repr2(i, g, n) for (int i = (int)(n)-1; i >= (g); i--) #define rep3(i, s, n, d) for (int i = (s); i < (int)(n); i += (d)) #define allpt(v) (v).begin(), (v).end() #define allpt_c(v) (v).cbegin(), (v).cend() #define allpt_r(v) (v).rbegin(), (v).rend() #define allpt_cr(v) (v).crbegin(), (v).crend() const int mod1 = 1e9 + 7, mod2 = 998244353, mod3 = 1e9 + 9; const int mod = mod2; const ll inf = 1e18; const string wsp = " "; const string tb = "\t"; const string rt = "\n"; const string alphabets = "abcdefghijklmnopqrstuvwxyz"; template void show1dvec(const vector &v) { if (v.size() == 0) return; int n = v.size() - 1; rep(i, n) cout << v[i] << wsp; cout << v[n] << rt; return; } void show2dvec(const vector &v) { int n = v.size(); rep(i, n) cout << v[i] << rt; } template void show2dvec(const vector> &v) { int n = v.size(); rep(i, n) show1dvec(v[i]); } template void range_sort(vector &arr, int l, int r) { sort(arr.begin() + l, arr.begin() + r); } template void show1dpair(const vector> &v) { int n = v.size(); rep(i, n) cout << v[i].first << wsp << v[i].second << rt; return; } template void pairzip(const vector> &v, vector &t, vector &s) { int n = v.size(); rep(i, n) { t.push_back(v[i].first); s.push_back(v[i].second); } return; } template void maxvec(vector &v) { T s = v[0]; int n = v.size(); rep(i, n - 1) { if (s > v[i + 1]) { v[i + 1] = s; } s = v[i + 1]; } } template bool myfind(T t, S s) { return find(t.cbegin(), t.cend(), s) != t.cend(); } bool check(int y, int x, int h, int w) { return 0 <= y && y < h && 0 <= x && x < w; } bool iskadomatsu(int a, int b, int c) { return (a != b && b != c && c != a) && ((a > b && b < c) || (a < b && b > c)); } double euc_dist(PII a, PII b) { return sqrt(pow(a.first - b.first, 2) + pow(a.second - b.second, 2)); } VS split(string s, char c) { VS ret; string part; s += c; rep(i, s.length()) { if (s[i] == c) { if (part != "") ret.emplace_back(part); part = ""; } else if (s[i] != c) { part += s[i]; } } return ret; } template ll pow_mod(T p, S q, R mod = 1ll) { ll ret = 1, r = p; while (q) { if (q % 2) ret *= r, ret %= mod; r = (r * r) % mod, q /= 2; } return ret % mod; } template ll pow_no_mod(T p, S q) { ll ret = 1, r = p; while (q) { if (q % 2) ret *= r; r = (r * r), q /= 2; } return ret; } void make_frac_tables(VL &frac_list, VL &frac_inv_list) { rep(i, frac_list.size() - 1) { frac_list[i + 1] *= frac_list[i] * (i + 1); frac_list[i + 1] %= mod; frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod); frac_inv_list[i + 1] %= mod; } } pair make_frac_tables(int n) { VL frac_list(n + 1, 1), frac_inv_list(n + 1, 1); rep(i, n) { frac_list[i + 1] *= frac_list[i] * (i + 1); frac_list[i + 1] %= mod; frac_inv_list[i + 1] *= frac_inv_list[i] * pow_mod(i + 1, mod - 2, mod); frac_inv_list[i + 1] %= mod; } return make_pair(frac_list, frac_inv_list); } ll comb(int a, int b, const VL &frac_list, const VL &frac_inv_list) { if (a < b) return 0; if (b < 0) return 0; ll ret = frac_list[a]; ret *= frac_inv_list[b]; ret %= mod; ret *= frac_inv_list[a - b]; ret %= mod; return ret; } struct vec2d { ll x; ll y; vec2d(ll _x, ll _y) { x = _x; y = _y; } ll dot(vec2d p) { return x * p.x + y * p.y; } vec2d diff(vec2d p) { return vec2d(x - p.x, y - p.y); } }; // void djkstra(int n, vector point_list, const VVL cost_list, // const VVI &connect) { // const ll llm = 1e18; // VVL min_cost(n, VL(n, llm)); // min_cost[0][0] = 0; // vector search = {make_pair(0, 0)}; // vector new_search; // while (!search.empty()) { // for (auto [p, q] : search) { // for (auto r : connect[p]) { // if (point_list[r] // .diff(point_list[p]) // .dot(point_list[q].diff(point_list[p])) <= 0 && // min_cost[r][p] > cost_list[r][p] + min_cost[p][q]) { // min_cost[r][p] = cost_list[r][p] + min_cost[p][q]; // new_search.emplace_back(make_pair(r, p)); // } // } // } // search.clear(); // search = new_search; // new_search.clear(); // // show1dvec(search); // // show1dvec(shortest); // } // auto ans = *min_element(allpt_c(min_cost[1])); // cout << ((ans == llm) ? -1 : ans) << rt; // // show2dvec(min_cost); // } struct node { int parent = -1; ll weight = 0; int depth = 0; int subtree = 1; VPII children; VPII connect; node(int n) { parent = -1; weight = 0; depth = 0; subtree = 1; children; connect; } }; struct graph { int _n; int root = 0; vector nodes; graph(int n) { _n = n; rep(i, _n) nodes.emplace_back(node(_n)); } void getconnect1() { int a, b; cin >> a >> b; a--, b--; nodes[a].connect.emplace_back(b, 0); nodes[b].connect.emplace_back(a, 0); } void getconnect2() { int a, b, c; cin >> a >> b >> c; a--, b--; nodes[a].connect.emplace_back(b, c); nodes[b].connect.emplace_back(a, c); } void showparent() { rep(i, _n - 1) cout << nodes[i].parent << wsp; cout << nodes[_n - 1].parent << rt; } void showweight() { rep(i, _n - 1) cout << nodes[i].weight << wsp; cout << nodes[_n - 1].weight << rt; } void showsubtree() { rep(i, _n - 1) cout << nodes[i].subtree << wsp; cout << nodes[_n - 1].subtree << rt; } void showdepth() { rep(i, _n - 1) cout << nodes[i].depth << wsp; cout << nodes[_n - 1].depth << rt; } }; struct point { int x; int y; point() { x = 0; y = 0; } point(int _x, int _y) { x = _x; y = _y; } void pointinput() { int _x, _y; cin >> _x >> _y; x = _x; y = _y; } void pointinv() { swap(x, y); } }; double pointseuc(point a, point b) { ll ax = a.x, bx = b.x, ay = a.y, by = b.y; return sqrt(pow(ax - bx, 2) + pow(ay - by, 2)); } ll pointseucsquare(point a, point b) { ll ax = a.x, bx = b.x, ay = a.y, by = b.y; return (ax - bx) * (ax - bx) + (ay - by) * (ay - by); } int pointsmanhattan(point a, point b) { return abs(a.x - b.x) + abs(a.y - b.y); } double dist_segment_point(TL3 segment, point p) { double a = get<0>(segment); double b = get<1>(segment); double c = get<2>(segment); return abs(a * p.x + b * p.y - c) / (a * a + b * b + c * c); } TL3 segment_parameter(point p, point q) { ll a, b, c; a = q.y - p.y; b = p.x - q.x; c = a * p.x + b * p.y; TL3 ret = (TL3){a, b, c}; // cout << a << b << c << rt; return ret; } int cross_check(TL3 segment, point p) { ll a = get<0>(segment); ll b = get<1>(segment); ll c = get<2>(segment); auto f = a * p.x + b * p.y - c; int ret; if (f > 0) ret = 1; if (f == 0) ret = 0; if (f < 0) ret = -1; return ret; } void shave(vector &v, int n) { if (n <= 1) return; vector w(n + 1, true); int x; w[0] = w[1] = false; rep2(i, 2, n + 1) { if (w[i]) { x = i * 2; while (x <= n) { w[x] = false; x += i; } } } rep(i, n + 1) if (w[i]) v.emplace_back(i); } // ll getpalindrome(int l, int r, const string &s, VL &memo) { // if (r - l <= 1) return 1; // if (memo[l] != -1) return memo[l]; // ll ret{1}; // int n = (r - l) / 2; // string sl, sr; // rep(i, n) { // sl += s[l + i]; // sr += s[r - 1 - i]; // string rsr(i + 1, '0'); // reverse_copy(allpt_c(sr), rsr.begin()); // // cout << sl << wsp << sr << wsp << rsr << rt; // if (sl == rsr) { // ret += getpalindrome(l + i + 1, r - i - 1, s, memo); // ret %= mod; // } // } // memo[l] = ret; // return ret; // } void getpalindrome(int l, int r, int n, const string &s, VVB &memo) { if (r - l <= 1 || s[l] == s[r - 1]) { memo[l][r] = true; if (l > 0 && r < n) { getpalindrome(l - 1, r + 1, n, s, memo); } } return; } template void coordinate_compress(vector &x, map &zip, int &xs) { sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end()); xs = x.size(); for (int i = 0; i < xs; i++) { zip[x[i]] = i; } x.shrink_to_fit(); } void dfs(int v, const VVI &connect, VI &parent, VI &check_list) { check_list.emplace_back(v); for (auto u : connect[v]) { if (parent[u] == -1 && parent[v] != u) { parent[u] = v; dfs(u, connect, parent, check_list); } } } ll sum(ll a) { ll b, c; if (a % 2 == 0) { b = a / 2; c = a + 1; } else { b = a; c = (a + 1) / 2; } return b * c; } int main() { cin.tie(0); ios::sync_with_stdio(false); // リアクティブ問題のときはコメントアウト #ifdef DEBUG cout << "DEBUG MODE" << endl; ifstream in("input.txt"); // for debug cin.rdbuf(in.rdbuf()); // for debug chrono::system_clock::time_point timestart, timeend; // for debug timestart = std::chrono::system_clock::now(); // for debug #endif int k; cin >> k; if (k == 0) { double pi = acos(-1); cout << (pi * pi / 6) << rt; return 0; } double ans{0}; rep(i, k) { ans += 1.0 / (1 + i); } ans /= k; cout << ans << rt; #ifdef DEBUG timeend = chrono::system_clock::now(); auto elapsed = chrono::duration_cast(timeend - timestart) .count(); cout << "Time is " << elapsed << "ms" << std::endl; #endif return 0; }