# include <bits/stdc++.h>
using namespace std;
# define db double
# define ll long long
# define pi 3.14159265359
# define rad(x) (x * pi / 180)
const int p_1[] = {1,-1};
const ll mod1 = 100000004987ll;
const int mod2 = 1e9 + 7;
const int mod3 = 666013;
const int mod4 = 997;
const int mod5 = 1000004123;
template < class T > inline T sqr(T x) {return x*x;}
template < class T > inline T min(T a,T b,T c) {return min(a,min(b,c));}
template < class T > inline T min(T a,T b,T c,T d) {return min(min(a,b),min(b,c));}
template < class T > inline T max(T a,T b,T c) {return max(a,max(b,c));}
template < class T > inline T max(T a,T b,T c,T d) {return max(max(a,b),max(b,c));}
template < class T > inline T det(T a,T b,T c,T d) {return a * c - b * d;}
template < class T > inline T det(T s[3][3])
{
    return - s[0][0] * det(s[1][1],s[1][2],s[2][1],s[2][2]) + s[0][1] * det(s[1][0],s[1][2],s[2][0],s[2][2]) - s[0][2] * det(s[1][0],s[1][1],s[2][0],s[2][1]);
}
template < class T1 , class T2 , class T3 > inline T3 pow(T1 a,T2 b,T3 mod) {T3 ans = 1;while (b){if (b&1) ans = (1LL * ans * a) % mod;a = (1LL * a * a) % mod;b >>= 1;}return ans;}
template < class T > T phi(T n){T cnt = n,p = n,ans = n;for (T i = 2;i*i <= p;++i)if (!(cnt%i)){ans /= i;ans *= (i-1);while (!(cnt%i)) cnt /= i;}if (cnt > 1) ans /= cnt,ans *= (cnt - 1);return ans;}
template < class T > T f(T a,T b) {return a < b ? 0 : a / b + f(a / b);}
template < class T > T gcd(T a,T b) {return __gcd(a,b);}
class Reader {
  public:
    Reader(const string& filename):
            m_stream(filename),
            m_pos(kBufferSize - 1),
            m_buffer(new char[kBufferSize]) {
        next();
    }

    Reader& operator>>(int& value) {
        value = 0;
        while (current() < '0' || current() > '9')
            next();
        while (current() >= '0' && current() <= '9') {
            value = value * 10 + current() - '0';
            next();
        }
        return *this;
    }

  private:
    const int kBufferSize = 32768;

    char current() {
        return m_buffer[m_pos];
    }

    void next() {
        if (!(++m_pos != kBufferSize)) {
            m_stream.read(m_buffer.get(), kBufferSize);
            m_pos = 0;
        }
    }

    ifstream m_stream;
    int m_pos;
    unique_ptr<char[]> m_buffer;
};
int v[100005];
ll a[100005];
ll b[100005];
ll p[100005];
const ll base = 400001;
const ll mod = mod1;
bool pali(int l,int r)
{
    ll left = (a[r] - a[l-1] * p[r - l] + base * mod) % mod;
    ll right = (b[r] - b[l-1] + mod) % mod;
    return left == right;
}
int main(void)
{
    ifstream fi("numarare.in");
    ofstream fo("numarare.out");
    int n;
    fi>>n;
    for (int i = 1;i <= n;++i) fi>>v[i];
    int nxt = v[n];
    for (int i = n - 1;i;--i)
    {
        int to = v[i];
        v[i] -= nxt;
        nxt = to;
    }
    --n;
    for (int i = 1;i <= n;++i) if (v[i] < 0) v[i] += 200000;
    p[0] = 1;
    for (int i = 1;i <= n;++i) p[i] = (p[i-1] * base) % mod;
    for (int i = 1;i <= n;++i) a[i] = (a[i-1] * base + v[i]) % mod;
    for (int i = 1;i <= n;++i) b[i] = (b[i-1] + p[i-1]*v[i]) % mod;
    ll ans = 0;
    for (int i = 1;i <= n;++i)
    {
        int l = i,r = i;
        for (int len = 65536;len;len >>= 1)
            if (l - len > 0 && r + len <= n && pali(l-len,r+len)) l -= len,r += len;
        ans += (r - l + 2) / 2;
    }
    return fo << ans << '\n',0;
}