#include <math.h>
#include<stdio.h>
int main()
{
    int n;
    scanf("%d", &n);
    int t;
    double x;
    int arr[200000];
    for (int i = 0; i < 200000; i++) {
        arr[i] = 0;
    }
    for (int i = 0; i < n; i++) {
        scanf("%lf %d", &x, &t);
        for (int j = 1; j <= t; j++) {
            double a = j * x;
            if (arr[(int)a] == 0) {
                arr[(int)a] = 1;
            }
            else {
                arr[(int)a] = 0;
            }
        }
    }
    for (int i = 1; i < 200000; i++) {
        if (arr[i] == 1) {
            printf("%d\n", i);
            break;
        }
    }
    return 0;
}