Author:  Иван Кобец  Time limit:  1 sec  
Input file:  Standard input  Memory limit:  512 Mb  
Output file:  Standard output 
The young programmer Ilya was presented with a sequence of numbers a_{i} of length n for his birthday. Ilya decided to select fine segments from this sequence. A fine segment is a sequence of successive elements of a_{i} containing some element equal to the sum of its first and last elements. For example, the sequence [1, 2, 5, 4] is fine because the sum of the leftmost and rightmost elements is 5, and the number 5 is in this sequence; the sequence [1, 2, 3, 4] is not fine because the sum of the leftmost and rightmost elements is 5, and the number 5 is not in this sequence. Your program must count the number of fine segments in a given sequence.
The first line contains an integer n — the length of the sequence. The second line contains n integers a_{i} — the elements of the sequence. All elements of the sequence are different.
Output a single integer — number of fine segments in the sequence.
1 ≤ n ≤ 10^{3}
1 ≤ a_{i} ≤ 10^{5}
First sample has one fine segment: [3, 7, 5, 4].
Second sample has two fine segments: [1, 5, 4] и [1, 5, 4, 7, 6].
No.  Standard input  Standard output 

1 


2 

