#include <bits/stdc++.h>
using namespace std;
int dp[1002][20002];
int main() {
  ios_base::sync_with_stdio;
  int n, m, x, y, i, j, a;
  cin >> n;
  long long ans = 0;
  for (i = 1; i <= n; i++) {
    cin >> a;
    for (j = 0; j < a; j++) {
      dp[i][j] = dp[i - 1][j + a];
    }
    for (j = 20000; j > 20000 - a; j--) {
      dp[i][j] = dp[i - 1][j - a];
    }
    for (j = a; j <= 20000 - a; j++) {
      dp[i][j] = (dp[i - 1][j - a] + dp[i - 1][j + a]) % 1000000007;
    }
    dp[i][10000 + a] = (dp[i][10000 + a] + 1) % 1000000007;
    ;
    dp[i][10000 - a] = (dp[i][10000 - a] + 1) % 1000000007;
    ans = (ans + dp[i][10000]) % 1000000007;
  }
  cout << ans;
  return 0;
}
