#!/usr/bin/env python3
m = [0] + [10**9]*4
for i in range(int(input())):
    x,y = [int(i) for i in input().split()]
    for dx in [-1,1]:
        for dy in [-1,1]:
            m[2*dx+dy] = min(m[2*dx+dy],dx*x+dy*y)
print(4 - sum(m) + (m[3] == -m[-3]) ^ (m[1] == -m[-1]))