//GPT 5.4-pro #include using namespace std; using u64 = unsigned long long; using u128 = __uint128_t; static constexpr int MOD = 998244353; static constexpr int INV2 = 499122177; // 2^{-1} static constexpr int INV6 = 166374059; // 6^{-1} static constexpr int INV30 = 432572553; // 30^{-1} int addmod(int a, int b) { int s = a + b; if (s >= MOD) s -= MOD; return s; } int submod(int a, int b) { int s = a - b; if (s < 0) s += MOD; return s; } int mulmod(long long a, long long b) { return int(a * b % MOD); } // a^k が limit を超えたら limit+1 を返す u64 ipow_limit(u64 a, int k, u64 limit) { u128 v = 1; for (int i = 0; i < k; ++i) { v *= a; if (v > limit) return limit + 1; } return (u64)v; } u64 isqrt_u64(u64 x) { long double d = sqrt((long double)x); u64 r = (u64)d; while ((u128)(r + 1) * (r + 1) <= x) ++r; while ((u128)r * r > x) --r; return r; } // G(n) = sum_{i=1}^n i * floor(sqrt(i)) mod MOD int G(u64 n) { if (n == 0) return 0; u64 m = isqrt_u64(n); u64 u = m - 1; // 完全ブロックは t=1..u int uu = int(u % MOD); // sum t^2 int s2 = mulmod(mulmod(uu, uu + 1LL), mulmod(2LL * uu + 1, INV6)); // sum t^3 int half = mulmod(mulmod(uu, uu + 1LL), INV2); int s3 = mulmod(half, half); // sum t^4 int poly = ((3LL * uu % MOD) * uu + 3LL * uu - 1) % MOD; if (poly < 0) poly += MOD; int s4 = mulmod( mulmod(mulmod(uu, uu + 1LL), 2LL * uu + 1), mulmod(poly, INV30) ); int full = (2LL * s4 + 3LL * s3 + s2) % MOD; // 末尾の不完全ブロック: m * sum_{i=m^2}^n i u64 a = m * m; int aa = int(a % MOD); int nn = int(n % MOD); int cnt = int((n - a + 1) % MOD); int tail_sum = mulmod(mulmod((aa + 1LL * nn) % MOD, cnt), INV2); return addmod(full, mulmod(int(m % MOD), tail_sum)); } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); u64 N; cin >> N; // base は最大でも floor((1e18)^(1/3)) = 1e6 const int MAXB = 1000000 + 5; // inv[x] = x^{-1} mod MOD vector inv(MAXB + 1); inv[1] = 1; for (int i = 2; i <= MAXB; ++i) { inv[i] = MOD - 1LL * (MOD / i) * inv[MOD % i] % MOD; } // events: (x=a^k, multiply by a/(a-1)) vector> events; events.reserve(1100000); for (int k = 3; k <= 60; ++k) { if (ipow_limit(2, k, N) > N) break; // これ以上の k は全部 1 for (u64 a = 2;; ++a) { u64 x = ipow_limit(a, k, N); if (x > N) break; events.push_back({x, mulmod(a % MOD, inv[a - 1])}); } } sort(events.begin(), events.end(), [](const auto& L, const auto& R) { return L.first < R.first; }); int ans = 0; int curH = 1; // 現在の H(i) u64 prev = 1; size_t i = 0; while (i < events.size()) { u64 x = events[i].first; // [prev, x-1] は H が一定 if (prev <= x - 1) { int seg = submod(G(x - 1), G(prev - 1)); ans = addmod(ans, mulmod(curH, seg)); } // x で起こるすべての更新をまとめて反映 while (i < events.size() && events[i].first == x) { curH = mulmod(curH, events[i].second); ++i; } prev = x; } if (prev <= N) { int seg = submod(G(N), G(prev - 1)); ans = addmod(ans, mulmod(curH, seg)); } cout << ans << '\n'; return 0; }