#include <map>

#include <cstdio>

#include <cstring>

#include <iostream>

#include <algorithm>

using namespace std;

const int MOD = 1e9+;

const int N = ;

int sum[N];

long long dp[N];

int main(){

    long long pre = ;

    map<long,long> records;

    int n; cin>>n; for(int i=;i<n;i++){

        scanf("%d",sum+i); if(i) sum[i]+=sum[i-];

        dp[i] = sum[i]?((pre+)%MOD):pre;

        auto iter = records.find(sum[i]);

        if(iter==records.end()) records[sum[i]]=dp[i];

        else {

            dp[i] = (dp[i]-iter->second+MOD)%MOD;

            iter->second = (iter->second+dp[i])%MOD;

        }

        pre = (pre+dp[i])%MOD;

    }

    printf("%lld\n",dp[n-]);

    return ;

}