#include #include const int Mod = 998244353, bit[21] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576}, bit_inv[21] = {1, 499122177, 748683265, 873463809, 935854081, 967049217, 982646785, 990445569, 994344961, 996294657, 997269505, 997756929, 998000641, 998122497, 998183425, 998213889, 998229121, 998236737, 998240545, 998242449, 998243401}, root[21] = {1, 998244352, 911660635, 372528824, 929031873, 452798380, 922799308, 781712469, 476477967, 166035806, 258648936, 584193783, 63912897, 350007156, 666702199, 968855178, 629671588, 24514907, 996173970, 363395222, 565042129}, root_inv[21] = {1, 998244352, 86583718, 509520358, 337190230, 87557064, 609441965, 135236158, 304459705, 685443576, 381598368, 335559352, 129292727, 358024708, 814576206, 708402881, 283043518, 3707709, 121392023, 704923114, 950391366}; void NTT_inline(int kk, int a[], int x[]) { int h, hh, i, ii, j, jj, k, l, r = bit[kk], d = bit[kk-1], tmpp, cur, prev; int *pi, *pii, *pj, *pjj; static int y[2][1048576]; long long tmp; for (i = 0; i < r; i++) y[0][i] = a[i]; for (k = 1, kk--, cur = 1, prev = 0; kk >= 0; k++, kk--, cur ^= 1, prev ^= 1) { for (h = 0, tmp = 1; h << (kk + 1) < r; h++, tmp = tmp * root[k] % Mod) { for (hh = 0, pi = &(y[cur][h<= Mod) *pi -= Mod; *pii = *pj - tmpp; if (*pii < 0) *pii += Mod; } } } for (i = 0; i < r; i++) x[i] = y[prev][i]; } void NTT_reverse_inline(int kk, int a[], int x[]) { int h, hh, i, ii, j, jj, k, l, r = bit[kk], d = bit[kk-1], tmpp, cur, prev; int *pi, *pii, *pj, *pjj; static int y[2][1048576]; long long tmp; for (i = 0; i < r; i++) y[0][i] = a[i]; for (k = 1, kk--, cur = 1, prev = 0; kk >= 0; k++, kk--, cur ^= 1, prev ^= 1) { for (h = 0, tmp = 1; h << (kk + 1) < r; h++, tmp = tmp * root_inv[k] % Mod) { for (hh = 0, pi = &(y[cur][h<= Mod) *pi -= Mod; *pii = *pj - tmpp; if (*pii < 0) *pii += Mod; } } } for (i = 0; i < r; i++) x[i] = y[prev][i]; } // Compute the product of two polynomials a[0-da] and b[0-db] using NTT in O(d * log d) time void prod_poly_NTT(int da, int db, int a[], int b[], int c[]) { int i, k; static int aa[1048576], bb[1048576], cc[1048576]; for (k = 0; bit[k] <= da + db; k++); for (i = 0; i <= da; i++) aa[i] = a[i]; for (i = da + 1; i < bit[k]; i++) aa[i] = 0; for (i = 0; i <= db; i++) bb[i] = b[i]; for (i = db + 1; i < bit[k]; i++) bb[i] = 0; static int x[1048576], y[1048576], z[1048576]; NTT_inline(k, aa, x); if (db == da) { for (i = 0; i <= da; i++) if (a[i] != b[i]) break; if (i <= da) NTT_inline(k, bb, y); else for (i = 0; i < bit[k]; i++) y[i] = x[i]; } else NTT_inline(k, bb, y); for (i = 0; i < bit[k]; i++) z[i] = (long long)x[i] * y[i] % Mod; NTT_reverse_inline(k, z, cc); for (i = 0; i <= da + db; i++) c[i] = (long long)cc[i] * bit_inv[k] % Mod; } // Compute the product of two polynomials a[0-da] and b[0-db] naively in O(da * db) time void prod_poly_naive(int da, int db, int a[], int b[], int c[]) { int i, j; static long long tmp[1048576]; for (i = 0; i <= da + db; i++) tmp[i] = 0; for (i = 0; i <= da; i++) for (j = 0; j <= db; j++) tmp[i+j] += (long long)a[i] * b[j] % Mod; for (i = 0; i <= da + db; i++) c[i] = tmp[i] % Mod; } // Compute the product of two polynomials a[0-da] and b[0-db] in an appropriate way void prod_polynomial(int da, int db, int a[], int b[], int c[]) { if (da <= 70 || db <= 70) prod_poly_naive(da, db, a, b, c); else prod_poly_NTT(da, db, a, b, c); } typedef struct { int key, id; } data; typedef struct { data obj[200001]; int size; } min_heap; void push(min_heap* h, data x) { int i = ++(h->size), j = i >> 1; data tmp; h->obj[i] = x; while (j > 0) { if (h->obj[i].key < h->obj[j].key) { tmp = h->obj[j]; h->obj[j] = h->obj[i]; h->obj[i] = tmp; i = j; j >>= 1; } else break; } } data pop(min_heap* h) { int i = 1, j = 2; data output = h->obj[1], tmp; h->obj[1] = h->obj[(h->size)--]; while (j <= h->size) { if (j < h->size && h->obj[j^1].key < h->obj[j].key) j ^= 1; if (h->obj[j].key < h->obj[i].key) { tmp = h->obj[j]; h->obj[j] = h->obj[i]; h->obj[i] = tmp; i = j; j <<= 1; } else break; } return output; } typedef struct Edge { struct Edge *next; int v; } edge; int main() { int i, N, M, u, w; edge *adj[200001] = {}, e[400001], *p; scanf("%d", &N); for (i = 0; i < N - 1; i++) { scanf("%d %d", &u, &w); e[i*2].v = w; e[i*2+1].v = u; e[i*2].next = adj[u]; e[i*2+1].next = adj[w]; adj[u] = &(e[i*2]); adj[w] = &(e[i*2+1]); } int par[200001] = {}, q[200001], head, tail; par[1] = 1; q[0] = 1; for (head = 0, tail = 1; head < tail; head++) { u = q[head]; for (p = adj[u]; p != NULL; p = p->next) { w = p->v; if (par[w] == 0) { par[w] = u; q[tail++] = w; } } } int j, ww, size[200001], *dp[200001], a[524288], b[524288], c[524288]; long long tmp; min_heap h; data d, dd, d_tmp; for (head--; head >= 0; head--) { u = q[head]; /* for (p = adj[u], size[u] = 1; p != NULL; p = p->next) { w = p->v; if (par[u] == w) continue; size[u] += size[w]; } dp[u] = (int*)malloc(sizeof(int) * (size[u] + 1)); dp[u][0] = 0; dp[u][1] = 1; for (i = 2; i <= size[u]; i++) dp[u][i] = 0; size[u] = 1; for (p = adj[u]; p != NULL; p = p->next) { w = p->v; if (par[u] == w) continue; for (i = size[u]; i > 0; i--) { for (j = 1, tmp = 0; j <= size[w]; j++) { dp[u][i+j] += (long long)dp[u][i] * dp[w][j] % Mod; if (dp[u][i+j] >= Mod) dp[u][i+j] -= Mod; tmp += (long long)dp[w][j] * j % Mod; } tmp %= Mod; dp[u][i] = dp[u][i] * tmp % Mod; } size[u] += size[w]; free(dp[w]); } */ h.size = 0; d.key = 1; d.id = u; push(&h, d); for (p = adj[u], size[u] = 1; p != NULL; p = p->next) { w = p->v; if (par[u] == w) continue; size[u] += size[w]; d.key = size[w]; d.id = w; push(&h, d); } dp[u] = (int*)malloc(sizeof(int) * 2); dp[u][0] = 0; dp[u][1] = 1; while (h.size >= 2) { d = pop(&h); dd = pop(&h); w = d.id; ww = dd.id; if (ww == u) { w ^= ww; ww ^= w; w ^= ww; d_tmp = dd; dd = d; d = d_tmp; } prod_polynomial(d.key, dd.key, dp[w], dp[ww], c); for (j = 1, tmp = 0; j <= dd.key; j++) tmp += (long long)dp[ww][j] * j % Mod; for (i = 0, tmp %= Mod; i <= d.key; i++) dp[w][i] = (c[i] + dp[w][i] * tmp) % Mod; d.key += dd.key; d.id = w; push(&h, d); dp[w] = (int*)realloc(dp[w], sizeof(int) * (d.key + 1)); for (; i <= d.key; i++) dp[w][i] = c[i]; free(dp[ww]); } } long long ans = 0; for (i = 1; i <= size[1]; i++) ans += (long long)dp[1][i] * i % Mod; printf("%lld\n", ans % Mod); fflush(stdout); return 0; }