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;
}