#include <stdio.h>
#include <stdlib.h>

double getSlope(int x1, int x2, int y1, int y2){
	if(x2 == x1){
		return 1.005;
	}
	double slope = (double)(y2 - y1)/(x2 - x1);
	return slope;
}

int getResult(double *v, int k){
	int total = 0;
	for(int i = 0; i < k -1; i++){
		for(int j = i + 1; j < k; j++){
			if(v[i] == v[j]){
				total++;
			}
		}
	}
	return total; 
}

int main(){
	FILE *in, *out;
	int N, k = 0;
	int arr_x[1000], arr_y[1000];
	double slopes[500500];
	in = fopen("trapez.in", "r");
	out = fopen("trapez.out", "w");
	fscanf(in, "%d", &N);
	if(N < 4){
		fprintf(out, "%d\n", 0);
		return 0;
	}

	for( int i = 0; i < N; i++){
		fscanf(in, "%d", &arr_x[i]);
		fscanf(in, "%d", &arr_y[i]);
	}

	for(int i = 0; i < N - 1; i++){
		for(int j = i + 1; j < N; j++){
			slopes[k++] = getSlope(arr_x[i], arr_x[j], arr_y[i], arr_y[j]);
		}
	}

	fprintf(out, "%d\n", getResult(slopes, k));
	return 0;
}