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 <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <cstring>
#define esp 1e-9
#define INF 1e8
#define mx 3000+10
using namespace std;

struct node
{
    int x,y;
} p[mx];
int n;
bool hash[2010][2010];

bool cmp(const node&a,const node&b)
{
    if(a.x!=b.x) return a.x<b.x;
    return a.y<b.y;
}

int main()
{
    while(~scanf("%d",&n))
    {
        int tx,ty;
        long long ans=0;
        memset(hash,0,sizeof(hash));
        for(int i=0; i<n; i++)
        {
            scanf("%d%d",&tx,&ty);
            if(tx<0) tx=-tx+1000;
            if(ty<0) ty=-ty+1000;
            p[i].x=tx,p[i].y=ty;
            ///scanf("%d%d",&p[i].x,&p[i].y);
            hash[p[i].x][p[i].y]=1;
        }
        sort(p,p+n,cmp);
        for(int i=0; i<n; i++)
            for(int j=i+1; j<n; j++)
            {
                if(i==j) continue;
                if((p[i].x+p[j].x)%2==0&&(p[i].y+p[j].y)%2==0)
                {
                    int x=(p[i].x+p[j].x)/2;
                    int y=(p[i].y+p[j].y)/2;
                    if(hash[x][y]) ans++;
                }
            }
        printf("%lld\n",ans);
    }
    return 0;
}


  			 			        		 	 	 	