#include #include #include #include #include #define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++) using namespace std; typedef long long int ll; typedef vector VI; typedef vector VL; typedef pair PI; const ll mod = 1e9 + 7; /* * Suffix Array. * Required Headers: algorithm, cassert, string, vector * Verified by: http://arc050.contest.atcoder.jp/submissions/818745 * Reference: http://mayokoex.hatenablog.com/entry/2016/04/03/145845 */ struct compare_sa { const std::vector &rank; int n, k; compare_sa(const std::vector &rank, int n, int k) : rank(rank), n(n), k(k) {} bool operator () (int i, int j) { if (rank[i] != rank[j]) { return rank[i] < rank[j]; } int ri = i + k <= n ? rank[i + k] : -1; int rj = j + k <= n ? rank[j + k] : -1; return ri < rj; } }; std::vector create_sa(const std::string& s) { int n = s.length(); std::vector sa(n + 1, -1); std::vector rank(n + 1, -1); std::vector tmp(n + 1, -1); for (int i = 0; i <= n; ++i) { sa[i] = i; rank[i] = i < n ? s[i] : -1; } for (int k = 1; k <= n; k *= 2) { compare_sa cp = compare_sa(rank, n, k); std::sort(sa.begin(), sa.begin() + n + 1, cp); tmp[sa[0]] = 0; for (int i = 1; i <= n; ++i) { tmp[sa[i]] = tmp[sa[i - 1]] + (cp(sa[i - 1], sa[i]) ? 1 : 0); } for (int i = 0; i <= n; ++i) { rank[i] = tmp[i]; } } return sa; } std::vector create_lcp(const std::string &s, const std::vector &sa) { int n = s.length(); std::vector rank(n + 1); std::vector lcp(n, -1); for (int i = 0; i <= n; ++i) { rank[sa[i]] = i; } int h = 0; lcp[0] = 0; for (int i = 0; i < n; ++i) { int j = sa[rank[i] - 1]; h = std::max(0, h - 1); for (; j + h < n && i + h < n; ++h) { if (s[j + h] != s[i + h]) { break; } } lcp[rank[i] - 1] = h; } return lcp; } std::vector > create_sparse_table(int n, const std::vector &lcp) { int h = 1; while ((1 << h) < n) { ++h; } std::vector > st(h + 1, std::vector(n)); for (int i = 0; i < n; ++i) { st[0][i] = lcp[i]; } for (int j = 1; j <= h; ++j) { for (int i = 0; i <= n - (1 << j); ++i) { st[j][i] = std::min(st[j - 1][i], st[j - 1][i + (1 << (j-1))]); } } return st; } int top_bit(int t) { for (int i = 31; i >= 0; --i) { if ((1 << i) & t) { return i; } } assert (0); } int get_lcp(const std::vector > &st, int f, int s) { if (f > s) { std::swap(f, s); } assert (f < s); int diff = top_bit(s - f); return std::min(st[diff][f], st[diff][s - (1 << diff)]); } const int N = 5001; int pal[N][N]; int pal2[N]; int main(void){ string s; cin >> s; string s_rev = s; reverse(s_rev.begin(), s_rev.end()); int n = s.length(); string t = s + "$" + s_rev; VI sa = create_sa(t); VI sa_inv(sa.size()); REP(i, 0, sa.size()) { sa_inv[sa[i]] = i; } VI lcp = create_lcp(t, sa); vector spt = create_sparse_table(2 * n + 1, lcp); REP(i, 0, n) { REP(j, i, n) { int idx1 = sa_inv[i]; int idx2 = sa_inv[n + 1 + (n - 1 - j)]; int comm_len = get_lcp(spt, idx1, idx2); if (0) { cerr << "idx1=" << idx1 << ", idx2=" << idx2 << endl; cerr << "lcp(s[" << i << "..], s[.." << j << "].rev) = " << comm_len; if (comm_len >= j - i + 1) { cerr << " pal"; } cerr << endl; } pal[i][j] = comm_len >= j - i + 1; } } REP(i, 0, n) { REP(j, 0, n) { pal2[j] += pal[0][i] * pal[i + 1][j]; } } ll tot = 0; REP(i, 0, n) { REP(j, i + 2, n) { tot += (ll)pal2[i] * pal[j][n - 1]; } } cout << tot << endl; }