def main():
    n = int(input())
    L = []
    for i in range(n):
        x, y = map(int, input().split())
        flag = True
        for l in L:
            if abs(x-l[0])**2 + abs(y-l[1])**2 < 400:
                flag = False
                break
        if flag:
            L.append([x, y])
    print(len(L))


if __name__ == '__main__':
    main()