vector<vector<bool>> field;
    field.resize(8);
    for (size_t i = 0; i < field.size(); ++i)
    {
        field[i].resize(8, false);
    }

    int n;
    cin >> n;

    while (n --> 0)
    {
        int x, y;
        cin >> x >> y;
        x--;
        y--;
        field[x][y] = true;
    }

    int p = 0;

    for (int i = 0; i < field.size(); ++i)
    {
        for (int j = 0; j < field[i].size(); ++j)
        {
            if (field[i][j])
            {
                int leftCheck = i - 1;
                int rightCheck = i + 1;
                int topCheck = j - 1;
                int bottomCheck = j + 1;

                if (leftCheck < 0)
                {
                    p++;
                }
                else
                {
                    if (!field[leftCheck][j]) p++;
                }

                if (rightCheck == 8)
                {
                    p++;
                }
                else
                {
                    if (!field[rightCheck][j]) p++;
                }

                if (topCheck < 0)
                {
                    p++;
                }
                else
                {
                    if (!field[i][topCheck]) p++;
                }

                if (bottomCheck == 8)
                {
                    p++;
                }
                else
                {
                    if (!field[i][bottomCheck]) p++;
                }

            }
        }
    }

    cout << p;

    return 0;