n = int(input())
XY = []
for i in range(n):
    x, y = map(int, input().split())
    XY.append((x, y))

if n == 1:
    print(0)
    exit()

import math
INF = float('inf')
D = [[INF]*n for _ in range(n)]
for i in range(n):
    x1, y1=XY[i]
    for j in range(n):
        if i == j:
            continue
        x2,y2 = XY[j]
        d = math.hypot(x1-x2, y1-y2)/2
        D[i][j] = d
#print(D)
ans = 0
used = set()
T = []
for i in range(1, n):
    T.append((D[0][i], i))
T.sort()
for d, i in T:
    for j in range(1, n):
        if j in used:
            continue
        if D[i][j] <= d:
            break
    else:
        ans += 1
        used.add(i)
print(ans)