数学感がある問題．参考にした提出．細かい条件
from sys import stdin
input = stdin.readline
n, w, h = map(int, input().strip().split())
xy = [list(map(int, input().strip().split())) for _ in range(n)]
ans = 0
for i in range(n):
for j in range(n):
for k in range(n):
for l in range(n):
if len(set((i, j, k, l))) != 4:
continue
o1 = (xy[i][0] - xy[j][0]) ** 2 + (xy[i][1] - xy[j][1]) ** 2
if not ((w - xy[i][0]) ** 2 < o1 or xy[i][0] ** 2 < o1 or (h - xy[i][1]) ** 2 < o1 or xy[i][1] ** 2 < o1):
o2 = (xy[k][0] - xy[l][0]) ** 2 + (xy[k][1] - xy[l][1]) ** 2
d = (xy[i][0] - xy[k][0]) ** 2 + (xy[i][1] - xy[k][1]) ** 2
if o1 - o2 - d >= 0 and o2 * d * 4 < (o1 - o2 - d) ** 2:
ans += 1
print(ans)
