n = int(input()) X = [0] * n Y = [0] * n for i in range(n): X[i], Y[i] = map(int, input().split()) dist = [] for i in range(n): for j in range(i + 1, n): dx = X[j] - X[i] dy = Y[j] - Y[i] dist.append((dx ** 2 + dy ** 2, i, j)) dist.sort() used = [False] * n ans = 0 for _, i, j in dist: if i == 0: if not used[j]: ans += 1 used[j] = True elif not used[i] and not used[j]: used[i] = used[j] = True print(ans)