You are given n integers a1, a2, ..., an. Find the number of pairs of indexes i, j (i < j) that ai + aj is a power of 2 (i. e. some integer x exists so that ai + aj = 2x).

Input

The first line contains the single positive integer n (1 ≤ n ≤ 105) — the number of integers.

The second line contains n positive integers a1, a2, ..., an (1 ≤ ai ≤ 109).

Output

Print the number of pairs of indexes i, j (i < j) that ai + aj is a power of 2.

Examples

Input

4
7 3 2 1


Output

2


Input

3
1 1 1


Output

3

Note

In the first example the following pairs of indexes include in answer: (1, 4) and (2, 4).

In the second example all pairs of indexes (i, j) (where i < j) include in answer.
#include <bits/stdc++.h>
using namespace std;
const int nax = 1e5 + 7;
map<long long, long long> psnt;
long long arr[nax];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> arr[i];
  }
  long long ans = 0;
  psnt.clear();
  for (int i = 0; i < n; ++i) {
    for (long long j = 1; j <= 2e9; j += j) {
      ans += psnt[j - arr[i]];
    }
    psnt[arr[i]]++;
  }
  cout << ans;
  return 0;
}
