codefdorce - Mike and Children

#include<bits/stdc++.h>
using namespace std;
#define fastread()(ios_base::sync_with_stdio(false),cin.tie(NULL))
#define ll long long
int main()
{
    fastread();
    int n,i,j;
    ll res = 0;
    cin>>n;
    int ara[n+1];
    for(i=0;i<n;i++)cin>>ara[i];
    map <ll,ll>mp;
    for(i=0;i<n;i++)
    {
        for(j=i+1;j<n;j++)
        {
            ll val = ara[i]+ara[j];
            mp[val]++;
            res= max(res,mp[val]);
        }
    }
    printf("%d\n",res);
    return 0;
}