N = int(input())

X = [list(map(int, input().split())) for i in range(N)]

D = []

for i in range(N):
    
    for j in range(i):
        
        D += [((X[i][0] - X[j][0]) ** 2 + (X[i][1] - X[j][1]) ** 2) * 10 ** 6 + i * 1000 + j]
        
D.sort()

x = [1] * N

ans = 0

for d in D:
    
    i = d % 1000
    j = d % 10 ** 6 // 1000
    
    if i == 0 and x[j]:
        x[j] = 0
        ans += 1
        
    elif x[i] and x[j]:
        
        x[i] = 0
        x[j] = 0
        
print(ans)