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;
template <class T>
T Mul(T x, T y, T P) {
  T F1 = 0;
  while (y) {
    if (y & 1) {
      F1 += x;
      if (F1 < 0 || F1 >= P) F1 -= P;
    }
    x <<= 1;
    if (x < 0 || x >= P) x -= P;
    y >>= 1;
  }
  return F1;
}
template <class T>
T Pow(T x, T y, T P) {
  T F1 = 1;
  x %= P;
  while (y) {
    if (y & 1) {
      F1 = Mul(F1, x, P);
    }
    x = Mul(x, x, P);
    y >>= 1;
  }
  return F1;
}
template <class T>
T Gcd(T x, T y) {
  if (y == 0) return x;
  T z;
  while (z = x % y) {
    x = y, y = z;
  }
  return y;
}
template <class T>
void UpdateMin(T &x, T y) {
  if (y < x) {
    x = y;
  }
}
template <class T>
void UpdateMax(T &x, T y) {
  if (x < y) {
    x = y;
  }
}
template <class T>
T Sqr(const T x) {
  return x * x;
}
template <class T>
T Abs(const T x) {
  return x < 0 ? -x : x;
}
class ReadBuffer {
 private:
  char buff[20000000];
  char *buf;

 public:
  void init(int size = 20000000) {
    fread(buff, 1, size, stdin);
    buf = buff;
  }
  template <class T>
  bool readInteger(T &x) {
    x = 0;
    while (*buf && isspace(*buf)) ++buf;
    if (*buf == 0) return false;
    static bool flag;
    flag = 0;
    if (*buf == '-')
      flag = true;
    else
      x = *buf - '0';
    while (isdigit(*++buf)) x = x * 10 + *buf - '0';
    if (flag) x = -x;
    return true;
  }
  template <class T>
  bool readFloat(T &x) {
    long double nowpos = 0.1;
    x = 0;
    while (*buf && isspace(*buf)) ++buf;
    if (*buf == 0) return false;
    static bool flag, decimal;
    decimal = flag = 0;
    if (*buf == '-')
      flag = true, ++buf;
    else if (*buf == '.')
      decimal = true;
    while (isdigit(*buf) || *buf == '.') {
      if (*buf == '.')
        decimal = true;
      else {
        if (decimal) {
          x += nowpos * (*buf - '0');
          nowpos *= 0.1;
        } else {
          x = x * 10 + *buf - '0';
        }
      }
      ++buf;
    }
    return true;
  }
  bool readChar(char c) {
    if (*buf == 0) return 0;
    return c = *buf++, 1;
  }
  bool readString(char *s) {
    while (*buf && isspace(*buf)) ++buf;
    if (!*buf) return false;
    while (!isspace(*buf)) *s++ = *buf++;
    *s++ = 0;
    return true;
  }
  int countSpacetonext() {
    int total = 0;
    while (*buf && *buf == ' ') ++total, ++buf;
    return total;
  }
  bool splitBycharactor(char *s, char Split = '\n') {
    while (*buf && *buf != Split) *s++ = *buf++;
    *s++ = 0;
    return *buf != 0;
  }
};
struct EDGE {
  int T;
  EDGE *Nxt;
};
int n;
map<int, int> M;
int ans;
int a[1001];
int main() {
  ans = 2;
  scanf("%d", &n);
  for (int i = 1; i <= (n); ++i) {
    scanf("%d", a + i);
    M[a[i]]++;
  }
  if (M.count(0)) ans = max(ans, M[0]);
  for (int i = 1; i <= (n); ++i)
    for (int j = 1; j <= (n); ++j)
      if (i != j && (a[i] || a[j])) {
        int A = a[i], B = a[j], cnt = 2, C;
        --M[A], --M[B];
        while (true) {
          C = A + B;
          if (M.count(C) && M[C] != 0) {
            --M[C], ++cnt;
            A = B, B = C;
          } else
            break;
        }
        ans = max(ans, cnt);
        A = a[i], B = a[j], cnt -= 2;
        ++M[A], ++M[B];
        while (cnt--) {
          C = A + B;
          ++M[C];
          A = B, B = C;
        }
      }
  printf("%d\n", ans);
  return 0;
}
