n=int(input())
aa,bb=[int(i) for i in input().split()]
s1=[]
s2=[]
s1.append(aa)
s2.append(bb)

for i in range(n-1):
    a=[int(_) for _ in input().split()]
    for j in range(len(s1)):
        if (s1[j]-a[0])**2 + (s2[j]-a[1])**2 < 400:
            break
        else:
            s1.append(a[0])
            s2.append(a[1])
print(len(s1))