#include <iostream>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> col(8, 0);
    vector<int> stroki(8, 0);
    vector<vector<char>> pole (8, vector<char>(8, '.'));
    for (int i = 0; i < n; ++i) {
        int x, y;
        cin >> x >> y;
        pole[x][y] = '*';
        ++col[x];
        ++stroki[y];
    }
    int cnt = 0;
    for (int i = 0; i < 8; ++i) {
        for (int j = 0; j < 8; ++j) {
            if (pole[i][j] == '*' && col[i] == 1 && stroki[j] == 1) {
                ++cnt;
            }
        }
    }
    cout << cnt;
    return 0;
}