#include <cstdio>
#include <vector>
#include <set>

using namespace std;

bool isPointAt[2002][2002];

int main(){
	int n;	
	scanf("%d", &n);
	vector<int> points;
	set<pair <int, int> > st;
	for(int i = 0; i < n; ++i){
		int a, b;
		scanf("%d%d", &a, &b);
		a += 1000; b += 1000;
		isPointAt[a][b] = true;
		points.push_back(a);
		points.push_back(b);
	}

	//int out = 0;

	for(int i = 0; i < 2 * n; i += 2){
		for(int j = 0; j < 2 * n; j += 2){
			if(i == j) continue;
			int deltaX = points[j] - points[i];
			int deltaY = points[j + 1] - points[i + 1];
			bool ok = true;
			for(int k = 0; k < 2 * n; k += 2){
				if(!(isPointAt[points[k] + deltaX][points[k + 1] + deltaY] || 
				     isPointAt[points[k] - deltaX][points[k + 1] - deltaY])){
					ok = false; break;
				}
			}
			if(ok){
//				printf("%d %d\n", deltaX, deltaY);
				st.insert(make_pair(deltaX, deltaY));
			}
		}
	}

	printf("%d\n", (int) st.size());
	return 0;
}