import math

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    
    N = int(data[0])
    if N == 0:
        print(0)
        return
    
    balloons = []
    index = 1
    for _ in range(N):
        x = int(data[index])
        y = int(data[index + 1])
        balloons.append((x, y))
        index += 2
    
    if N == 1:
        print(0)
        return
    
    count = 0
    for i in range(1, N):
        xi, yi = balloons[i]
        d_i = math.hypot(xi - balloons[0][0], yi - balloons[0][1])
        found = False
        for j in range(1, N):
            if i == j:
                continue
            xj, yj = balloons[j]
            dist_ij = math.hypot(xi - xj, yi - yj)
            if dist_ij < d_i:
                d_j1 = math.hypot(xj - balloons[0][0], yj - balloons[0][1])
                if d_j1 > dist_ij:
                    found = True
                    break
        if found:
            count += 1
    
    print(N - 1 - count)

if __name__ == '__main__':
    main()