#include <bits/stdc++.h>
using namespace std;

int main() {
	int n; cin >> n;
	vector<int> arr(n);
	for(int i = 0; i < n; i++)
	cin >> arr[i];
	
	int res = INT_MIN;
	
	for(int i = 0; i < n; i++){
		for(int j = i+1; j < n; j++){
			int l = arr[i]+arr[j];
			
			unordered_map<int,int> mp;
	        for(int k = 0; k < n; k++){
	            mp[arr[k]]++;
	        }
	        int ans = 0;
	        unordered_map<int,int> vis;
	        for(auto k : mp){
	            int val = k.first;
	            int freq = k.second;
	            int req = l-val;
	            if(vis.find(val) != vis.end() || vis.find(req) != vis.end())
	            continue;
	            if(mp.find(req) != mp.end()){
	                if(val == req)
	                ans += freq/2;
	                else{
	                    ans += min(freq, mp[req]);
	                }
	                vis[req]++;
	                vis[val]++;
	            }
	        }
	        res = max(res,ans);
		}
	}
	cout << res;
	return 0;
}