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.
from collections import Counter,defaultdict,deque
#import heapq as hq
#import itertools
from operator import itemgetter
#from itertools import count, islice
#from functools import reduce
#alph = 'abcdefghijklmnopqrstuvwxyz'
#from math import factorial as fact
#a,b = [int(x) for x in input().split()]
#sarr = [x for x in input().strip().split()]
import math
import sys
input=sys.stdin.readline
def solve():
    n = int(input())
    arr = [int(x) for x in input().split()]
    d = defaultdict(int)
    res = 0
    for el in arr:
        for p in range(32):
            res+=d[(1<<p)-el]
        d[el]+=1
    print(res)
        

tt = 1#int(input())
for test in range(tt):
    solve()















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