Yash has recently learnt about the Fibonacci sequence and is very excited about it. He calls a sequence Fibonacci-ish if 

  1. the sequence consists of at least two elements 
  2. f0 and f1 are arbitrary 
  3. fn + 2 = fn + 1 + fn for all n ≥ 0. 



You are given some sequence of integers a1, a2, ..., an. Your task is rearrange elements of this sequence in such a way that its longest possible prefix is Fibonacci-ish sequence.

Input

The first line of the input contains a single integer n (2 ≤ n ≤ 1000) — the length of the sequence ai.

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

Output

Print the length of the longest possible Fibonacci-ish prefix of the given sequence after rearrangement.

Examples

Input

3
1 2 -1


Output

3


Input

5
28 35 7 14 21


Output

4

Note

In the first sample, if we rearrange elements of the sequence as  - 1, 2, 1, the whole sequence ai would be Fibonacci-ish.

In the second sample, the optimal way to rearrange elements is <image>, <image>, <image>, <image>, 28.
#include <bits/stdc++.h>
using namespace std;
long long int func(long long int la, long long int sla,
                   unordered_map<long long int, long long int> &fr,
                   vector<long long int> &vec, long long int n) {
  long long int c = 2LL;
  fr[la]--;
  fr[sla]--;
  vector<long long int> fi;
  fi.push_back(la);
  fi.push_back(sla);
  while (fr[la + sla] > 0LL) {
    fr[la + sla]--;
    fi.push_back(la + sla);
    c += 1LL;
    long long int la1 = la + sla;
    sla = la;
    la = la1;
  }
  for (long long int i = 0LL; i < fi.size(); i++) {
    fr[fi[i]]++;
  }
  return c;
}
int main() {
  long long int n;
  scanf("%lld", &n);
  vector<long long int> vec;
  unordered_map<long long int, long long int> fr;
  for (long long int i = 0LL; i < n; i++) {
    long long int a;
    scanf("%lld", &a);
    vec.push_back(a);
    fr[a]++;
  }
  long long int maxi = 2LL;
  for (long long int i = 0LL; i < n - 1LL; i++) {
    for (long long int j = i + 1LL; j < n; j++) {
      if (vec[i] == 0LL && vec[j] == 0LL) {
        maxi = max(maxi, fr[0LL]);
      } else {
        long long int a = func(vec[i], vec[j], fr, vec, n);
        long long int b = func(vec[j], vec[i], fr, vec, n);
        maxi = max(maxi, a);
        maxi = max(maxi, b);
      }
    }
  }
  printf("%lld\n", maxi);
}
