n=int(input())
s=[]
s.append([int(i) for i in input().split()])

for i in range(n-1):
    a=[int(_) for _ in input().split()]
    for j in range(len(s)):
        if (s[j][0]-a[0])**2 + (s[j][1]-a[1])**2 < 400:
            break
        else:
            s.append(a)

print(len(s))