#include <stdio.h>
int main()
{
    int n;
    double a[5001];
    int ax[5001];
    int t[5001];
    int max=0;
    int N[2000001] = { 0 };
    int number=0;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        scanf("%lf%d", &a[i], &t[i]);
        ax[i] = (int)a[i];
        if (ax[i] * t[i] > max)
        {
            max = ax[i] * t[i];
        }
    }
    for (int x = 1; x <= n; x++)
    {
        for (int y = 1; y <= t[x]; y++)
        {
            if (N[y * ax[x]] == 0)
            {
                N[y * ax[x]] = 1;
            }
            else
            {
                N[y * ax[x]] = 0;
            }
        }
    }
    for (int k = 1; k <= max; k++)
    {
        if (N[k] == 1)
        {
            number = k;
        }
    }
    printf("%d", number);
    return 0;
}