#include <iostream>
#include <algorithm>

#define foreach(T,p,c) for(T p = (c).begin(); p != (c).end(); p++)

#define NW_SE(x,y) nw_se[(x)+(y)]
#define NE_SW(x,y) ne_sw[(x)-(y)+(n-1)]

using namespace std;

int main(void)
{
	int n;
	cin >> n;

	int y[50];
	bool nw_se[99], ne_sw[99];

	fill_n(y, n, -1);
	fill_n(nw_se, n * 2 - 1, false);
	fill_n(ne_sw, n * 2 - 1, false);

	for(int i = 0; i < n; i++) {
		int u, v;
		cin >> u >> v;
		--u, --v;
		if(y[u] >= 0 || NW_SE(u,v) || NE_SW(u,v)) u /= (u - u);
		y[u] = v;
		NW_SE(u,v) = NE_SW(u,v) = true;
	}

	int m = 0;
	for(int i = 0; i < n; i++) {
		NW_SE(i,y[i]) = NE_SW(i,y[i]) = false;
		for(int j = i + 1; j < n; j++) {
			NW_SE(j,y[j]) = NE_SW(j,y[j]) = false;
			for(int k = j + 1; k < n; k++) {
				NW_SE(k,y[k]) = NE_SW(k,y[k]) = false;

				if(!NW_SE(i,y[j]) && !NE_SW(i,y[j])) {
					NW_SE(i,y[j]) = NE_SW(i,y[j]) = true;
					if(!NW_SE(j,y[k]) && !NE_SW(j,y[k])) {
						NW_SE(j,y[k]) = NE_SW(j,y[k]) = true;
						if(!NW_SE(k,y[i]) && !NE_SW(k,y[i])) ++m;
						NW_SE(j,y[k]) = NE_SW(j,y[k]) = false;
					}
					NW_SE(i,y[j]) = NE_SW(i,y[j]) = false;
				}

				if(!NW_SE(i,y[k]) && !NE_SW(i,y[k])) {
					NW_SE(i,y[k]) = NE_SW(i,y[k]) = true;
					if(!NW_SE(j,y[i]) && !NE_SW(j,y[i])) {
						NW_SE(j,y[i]) = NE_SW(j,y[i]) = true;
						if(!NW_SE(k,y[j]) && !NE_SW(k,y[j])) ++m;
						NW_SE(j,y[i]) = NE_SW(j,y[i]) = false;
					}
					NW_SE(i,y[k]) = NE_SW(i,y[k]) = false;
				}

				NW_SE(k,y[k]) = NE_SW(k,y[k]) = true;
			}
			NW_SE(j,y[j]) = NE_SW(j,y[j]) = true;
		}
		NW_SE(i,y[i]) = NE_SW(i,y[i]) = true;
	}

	cout << m << endl;
	return 0;
}