10
-2 1
2 -2
-1 -2
0 0
2 -1
0 -2
2 2
0 2
-1 -1
1 -2
 40
-8 24
2 -1
1 -18
72 -70
5 -4
-308 436
-19 40
36 -35
-178 265
-1 2
-7 30
-1 0
3 -2
200 -285
17 -16
-35 74
0 -4
-86 106
-1 4
-7 6
0 1
-5 4
-2 3
6 -5
-4 5
181 -262
76 -118
0 0
-7 18
-58 104
-5 6
-6 12
-3 4
1 0
11 -10
-86 130
-3 6
153 -236
-183 270
-33 64
 5
0 -1
0 -2
0 -3
0 -4
0 -5
 10
0 1
-1 -1
1 1
-1 0
1 -1
-2 -1
-2 2
-2 0
0 -2
0 -1
 20
-1 18
-2 5
-5 4
2 -33
9 -18
0 0
11 -22
2 0
-1 2
-4 41
1 6
1 -2
6 -12
0 1
-3 6
3 -6
3 -8
-1 4
2 -5
1 0
 10
2 1
-1 0
-2 -1
-1 1
0 2
2 -2
0 0
-2 -2
0 -2
-2 1
 20
-3 -3
0 4
-3 1
1 1
-1 2
-4 4
3 -1
-3 0
0 2
4 0
2 3
2 4
4 -3
-4 3
-1 1
1 3
-2 4
1 -2
1 -1
3 0
 3
0 0
0 -1
0 1
 10
2 1
-1 1
0 0
-3 1
-2 -3
-1 -2
-1 -1
1 2
3 -2
0 -2
 3
3 3
1 2
1 1
 4
0 0
1 0
2 0
3 0
 9
1 1
1 0
0 1
0 0
-1 0
-1 1
-1 -1
1 -1
0 -1
 7
1 1
-1 -1
1 0
0 1
-1 0
0 -1
0 0

4
 57
 4
 5
 21
 4
 10
 1
 1
 0
 2
 8
 3

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long int
#define f(i,a,n) for(ll i=a;i<n;i++)
#define vi vector<int>
#define MAX 500001
#define vi_ll vector<long long int>
#define mod 1000000007
#define fi first
#define se second
#define ull unsigned long long int
#define FIO ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define all(a) a.begin(),a.end()
#define mp make_pair

const double pi = acos(-1);
vi_ll prime(10000001,1);
const int N=2e5+5;
ll max(ll a,ll b)
{
	if(a<b)a=b;
	return a;
}
ll min(ll a,ll b)
{
	if(a<b)return a;
	return b;
}
ll lcm(ll a,ll b)
{
	return ((a*b)/__gcd(a,b));
}
void init()
{
	//fill(prime,prime+10000001,1);
	prime[0]=1,prime[1]=0;
	ll no=sqrt(10000001);
	f(i,2,no+1)
	{
		if(prime[i])
		{
			for(ll j=2;i*j<=10000001;j++)
			{
				prime[i*j]=0;
			}
		}
	}
	return;
}
bool mycomp(const pair<ll,ll> &a,const pair<ll,ll> &b)
{
	return a.fi<b.fi;
}
int main()
{
	FIO
	ll n,no1,no2,ans=0; cin>>n; vector<pair<ll,ll>>p; map<pair<ll,ll>,bool>m;
	f(i,0,n)
	{
		cin>>no1>>no2;
		p.pb(mp(no1,no2));
		m[{no1,no2}]=true;
	}
	
	f(i,0,n-2)
	{
		f(j,i+2,n)
		{
			no1=(p[i].fi+p[j].fi)/2;
			no2=(p[i].se+p[j].se)/2;
			
			if((p[i].fi+p[j].fi)%2||(p[i].se+p[j].se)%2)
			continue;
			
			if(m.find({no1,no2})!=m.end())
			ans++;
		}
	}
	
	cout<<ans<<endl;
	
}