import multiprocessing
import sys

def verify_special_property(point1,points_coord,nr_of_triangles):
    for point2 in range (point1+1,len(points_coord)):
        if abs(points_coord[point1][0]-points_coord[point2][0])==abs(points_coord[point1][1]-points_coord[point2][1]):
            if [points_coord[point1][0],points_coord[point2][1]] in points_coord:
                nr_of_triangles.value+=1
            if [points_coord[point2][0],points_coord[point1][1]] in points_coord:
                nr_of_triangles.value+=1

if __name__ == '__main__':
    nr_of_points=int(sys.stdin.readline())
    points_coord=[]
    for i in range (0,nr_of_points):
        coord=sys.stdin.readline().split()
        points_coord+=[[int(coord[0]),int(coord[1])]]
    nr_of_triangles=multiprocessing.Value('i', 0)
    li=[]
    for point1 in range (0,(len(points_coord))-1):
        li.append(multiprocessing.Process(target=verify_special_property, args=(point1,points_coord,nr_of_triangles)))
        li[point1].start()
    for p in li:
        p.join()
    sys.stdout.write(str(nr_of_triangles.value))