#include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x ostream& operator<<(ostream& os, const pair& p){ return os << "{" << p.first << ", " << p.second << "}"; } template ostream& operator<<(ostream& os, const vector& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } template ostream& operator<<(ostream& os, const set& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } template ostream& operator<<(ostream& os, const map& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } #ifdef ONLINE_JUDGE #define dump(expr) ; #else #define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; } #endif const ll mod = 1000000007; struct mint { ll x; mint(ll x_ = 0) : x((x_ % mod + mod) % mod) {} mint operator-() const { return mint(-x); } mint &operator+=(const mint &a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint &operator-=(const mint &a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; } mint &operator*=(const mint &a) { (x *= a.x) %= mod; return *this; } mint operator+(const mint &a) const { mint res(*this); return res += a; } mint operator-(const mint &a) const { mint res(*this); return res -= a; } mint operator*(const mint &a) const { mint res(*this); return res *= a; } mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; } mint inv() const { return pow(mod - 2); } mint &operator/=(const mint &a) { return (*this) *= a.inv(); } mint operator/(const mint &a) const { mint res(*this); return res /= a; } friend ostream &operator<<(ostream &os, const mint &m) { os << m.x; return os; } friend istream &operator>>(istream &is, mint &m) { is >> m.x; return is; } }; template struct PrefixSum { vector sums; PrefixSum(vector vs) { int n = (int)vs.size(); sums.resize(n + 1, (T)0); for (int i : range(n)) sums[i + 1] = sums[i] ^ vs[i]; } T sum(int i, int j) { // vs[i] + ... + vs[j] if (i > j) return (T)0; return sums[j + 1] ^ sums[i]; } }; ll brute(int n, vector vs) { vector dp(n + 1); /* dp[n] = 1; for (int k = n - 1; k >= 0; --k) { for (int p = k + 1; p <= n; ++p) { int tot = 0; for (int r = p - 1; r > k; --r) { tot ^= vs[r]; if (tot == 0) goto SKIP; } dp[k] += dp[p]; SKIP:; } } */ for (int k = n - 1; k >= 0; --k) { dp[k] = 1; for (int p = k + 1; p < n; ++p) { int tot = 0; for (int r = p - 1; r > k; --r) { tot ^= vs[r]; if (tot == 0) goto SKIP; } dp[k] += dp[p]; SKIP:; } } dump(dp); return dp[0].x; } ll solve() { int n; cin >> n; vector vs(n); for (int i : range(n)) cin >> vs[i]; dump(brute(n, vs)); auto ps = PrefixSum(vs); map mp; vector nexts(n, -1); for (int i = n - 1; i >= 0; --i) { int sum = ps.sum(0, i); if (mp.count(sum)) { nexts[i] = mp[sum]; } mp[sum] = i; } dump(nexts); vector dp(n); mint total = 0; for (int k = n - 1; k >= 0; --k) { dp[k] = 1; if (nexts[k] >= 0) total -= dp[nexts[k] + 1]; dp[k] += total; total += dp[k]; } dump(dp); return dp[0].x; } int main() { cout << fixed << setprecision(12); cout << solve() << endl; }