using namespace std;
bool light[2000001];
double a;
double b;
int main()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> a >> b;
        for (double j = 1; j <= b; ++j)
        {
            if (light[int(j * a)] == 0)
            {
                light[int(j * a)] = 1;
            }
            else
            {
                light[int(j * a)] = 0;
            }
        }
    }
    for (int i = 1; i <= n; i++)
    {
        if (light[i] == 1)
        {
            cout << i;
            break;
        }
    }
    return 0;
}