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#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
using namespace std;

long long tab[300009];
set<int> sums;
long long fenwick[2][2][600009], fen_sum[2][2];
const long long M = 1e9 + 7;
map<long long, long long> przen;

// -----------Fenwick tree implementation based on Wikipedia------------
long long prefix_sum(int i, int j, long long b)
{
	long long su = fenwick[i][j][0] % M;
	for(int k=b; k>0; k=k-(k&(-k)))
	{
		su = (su + fenwick[i][j][k]) % M;
	}
	return su;
}

void add(int i, int j, long long b, long long w)
{
	fen_sum[i][j] = (fen_sum[i][j] + w) % M;
	if(b == 0)
	{
		fenwick[i][j][b] = (fenwick[i][j][b] + w) % M;
		return;
	}
	for(int k=b; k<524288; k=k+(k&(-k)))
	{
		fenwick[i][j][k] = (fenwick[i][j][k] + w) % M;
	}
}
// ---------------------------------------------------------------------

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	long long n, a = 0, b = 0, c, w, w1, w2, w3, w4;
	cin>>n;
	for(int i=1; i<=n; i++) cin>>tab[i];
    sums.insert(0);
	for(int i=1; i<=n; i++)
	{
		b += tab[i];
		while(b >= M)
		{
			b -= M;
			a++;
		}
		sums.insert(b);
	}
	a = 0;
	for(auto s : sums)
	{
		przen[s] = a;
		a++;
	}
	
	a = b = 0;
	fenwick[0][0][0] = 1;
	fen_sum[0][0] = 1;
	for(int i=1; i<=n; i++)
	{
		b += tab[i];
		while(b >= M)
		{
			b -= M;
			a++;
		}
		c = przen[b];
		w1 = prefix_sum(a%2, b%2, c);
		w2 = prefix_sum(1-(a%2), 1-(b%2), c);
		w3 = prefix_sum(a%2, 1-(b%2), c);
		w4 = prefix_sum(1-(a%2), b%2, c);
		w2 = fen_sum[1-(a%2)][1-(b%2)] - w2;
		w3 = fen_sum[a%2][1-(b%2)] - w3;
		while(w2 < 0) w2 += M;
		while(w3 < 0) w3 += M;
		w1 = (w1 + w2) % M;
		w3 = (w3 + w4) % M;
		w = (w1 + w3) % M;
		add(a%2, b%2, c, w);
	}
	c = przen[b];
	cout<<w  % M;
	return 0;
}