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#include <bits/stdc++.h>

using namespace std;

const int N = 1'000'007;
const int M = 1e9 + 7;
const int T = 1 << 20;

int add(int a, int b) { return a += b, a < M ? a : a - M; }
int sub(int a, int b) { return a -= b, a < 0 ? a + M : a; }

struct Node {
    int odd;
    int even;
    int left;
};

Node operator+ (const Node &a, const Node &b) {

    Node res{0, 0, a.left};

    //cerr << "adding: (" << a.left << ' ' << a.odd << ' ' << a.even << ") (" << b.left << ' ' << b.odd << ' ' << b.even << ")\n";

    if((b.left - a.left) & 1) {
        res.even = add(a.even, b.odd);
        res.odd  = add(a.odd,  b.even);
    }
    else {
        res.even = add(a.even, b.even);
        res.odd  = add(a.odd,  b.odd);
    }

    return res;

}

Node tree[T << 1];

int n, m, a[N], s[N], ways[N], offset;

void upd(int p, int v) {

    //cerr << "> " << p << " -> ";
    p = lower_bound(s, s + m, p) - s;

    //cerr << p << " v = " << v << '\n';

    tree[p + T].even = add(tree[p + T].even, v);

    for(p += T; p >>= 1; )
        tree[p] = tree[p << 1 | 0] + tree[p << 1 | 1];
}

Node sum(int l, int r) {

    //cerr << "> " << l << ' ' << r << " -> ";

    Node L{0, 0, l};
    Node R{0, 0, 0};

    l = lower_bound(s, s + m, l) - s;
    r = upper_bound(s, s + m, r) - s - 1;

    //cerr << l << ' ' << r << '\n';

    // cerr << "sum: " << l << ' ' << r << '\n';

    for(l += T, r += T + 1; l < r; l >>= 1, r >>= 1) {
        if(l & 1)   L = L + tree[l++];
        if(r & 1)   R = tree[--r] + R;
    }

    // cerr << "= " << (L + R).odd << ' ' << (L + R).even << '\n';
    // cerr << '\n';

    return L + R;
}

int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);

    cin >> n;
    for(int i = 0; i < n; i++)
        cin >> a[i];

    s[0] = sub(0, a[0]);
    for(int i = 1; i < n; i++)
        s[i] = sub(s[i - 1], a[i]);

    for(int i = n; i < 2 * n; i++) {
        s[i] = sub(s[i - n], 1);
    }

    s[2 * n] = M - 1;

    // cerr << "p: ";
    // for(int i = 0; i < 2 * n + 2; i++) {
    //    cerr << s[i] << ' ';
    //}
    //cerr << '\n';

    sort(s, s + 2 * n + 2); 
    m = unique(s, s + 2 * n + 2) - s;

    //cerr << "s: ";
    //for(int i = 0; i < m; i++)
    //    cerr << s[i] << ' ';
    //cerr << '\n';

    for(int i = 0; i < m; i++)
        tree[i + T].left = s[i];

    for(int i = m; i < T; i++)
        tree[i + T].left = M;

    for(int i = T - 1; i; i--)
        tree[i].left = tree[i << 1 | 0].left;

    upd(0, 1);
    
    for(int i = 0; i < n; i++) {

        offset = sub(offset, a[i]);

        //cerr << "offset: " << offset << '\n';

        //cerr << "----\n";
        ways[i] = sum(offset, M - 1).even;  

        if(offset & 1)
            ways[i] = add(ways[i], sum(0, offset - 1).even);
        else
            ways[i] = add(ways[i], sum(0, offset - 1).odd);

        //cerr << "----\n";
        //cerr << i << ":\n"; 
        //cerr << sum(offset, T - 1).even << ' ' << sum(offset, T - 1).odd << '\n';
        //cerr << sum(0, offset - 1).even << ' ' << sum(0, offset - 1).odd << '\n';
        //cerr << '\n';

        // ways[i] = add(sum(offset, T - 1).even, sum(0, offset - 1).odd);

        upd(offset, ways[i]);

        //cerr << "ways[" << i << "] = " << ways[i] << '\n';

    }

    cout << ways[n - 1] << '\n';
}