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#include <bits/stdc++.h>
using namespace std;
const int mod=1e9+7;

struct Node
{
    int sum[2];
    Node *left;
    Node *right;
};

void Extend(Node *v)
{
    v->left=new Node();
    v->right=new Node();
}

void Update(Node *v, int bl, int br, int p, int w)
{
    v->sum[p&1]+=w;
    if(v->sum[p&1]>=mod)v->sum[p&1]-=mod;
    if(bl==br)return;
    int bm=(bl+br)/2;
    if(v->left==nullptr)Extend(v);
    if(p<=bm)Update(v->left, bl, bm, p, w);
    else Update(v->right, bm+1, br, p, w);
}

int Query(Node *v, int bl, int br, int l, int r, char type)
{
    if(bl>r || br<l)return 0;
    if(bl>=l && br<=r)return v->sum[type];
    int bm=(bl+br)/2;
    if(v->left==nullptr)Extend(v);
    int res=Query(v->left, bl, bm, l, r, type) + Query(v->right, bm+1, br, l, r, type);
    if(res>=mod)res-=mod;
    return res;
}

int main()
{
    ios_base::sync_with_stdio(0);
    Node *root=new Node();
    Update(root, 0, mod-1, 0, 1);
    int n;
    cin>>n;
    int val=0;
    int sum=0;
    for(int i=0;i<n;i++)
    {
        int a;
        cin>>a;
        sum+=a;
        if(sum>=mod)sum-=mod;
        val=Query(root, 0, mod-1, 0, sum, sum&1);
        if(sum+1<mod)val+=Query(root, 0, mod-1, sum+1, mod-1, (sum+1)&1);
        if(val>=mod)val-=mod;
        Update(root, 0, mod-1, sum, val);
    }
    cout<<val<<endl;
}