how many continuous segment of sum zero

/* how many continuous segment of sum zero cf 383D  sign is not given we can take any sign on any number */
ll dp[1001][20051],ans;ll arr[MAX];


int main()
{
    booster()
    //read("input.txt");

    int n;
    cin>>n;
    for(int i = 1;i<=n;i++)cin>>arr[i];
    dp[0][0] = 1;
    for(int i = 0;i<=n;i++)dp[i][0] = 1;
    for(int i = 1;i<=n;i++){
        for(int j = 0;j<=10000;j++){
            if(j>=arr[i])
            dp[i][j] += dp[i-1][j-arr[i]] + dp[i-1][j+arr[i]];
            else dp[i][j] += dp[i-1][arr[i] - j] + dp[i-1][j+arr[i]];
            if(dp[i][j]>=mod)dp[i][j]%=mod;
        }
        ans+=dp[i][0] - 1;
        if(ans<0)
        ans += mod;
        if(ans>=mod)ans%=mod;
    }

    cout<<ans;


    return 0;
}