import sys
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=0
for point1 in range (0,(len(points_coord))-1):
    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+=1
            if [points_coord[point2][0],points_coord[point1][1]] in points_coord:
                nr_of_triangles+=1
sys.stdout.write(str(nr_of_triangles))