#include<stdio.h>
#include<stdlib.h>

int main()
{
    int n, t;
    double a;
    scanf("%d", &n);
    int* p = (int*)calloc(2000001,4);

    for (int i = 0; i < n; i++)
    {
        scanf("%lf %d", &a, &t);
        for (int j = 1; j <= t; j++)
        {
            if (p[int(a * j)] == 0)
            {
                p[int(a * j)] = 1;
            }
            if(p[int(a*j)]==1)
            {
                p[int(a * j)] = 0;
            }
        }
    }
    for (int i = 0;; i++)
    {
        if (p[i] == 1)
        {
            printf("%d\n", i);
            break;
        }

        free(p);
        
    }
    return 0;
}