#include<bits/stdc++.h> //万能头文件
using namespace std;
int main() {
    int n;
    cin>>n;
    int arr[2000001] = {0};
    for (int i = 0; i < n; i++) {
        float a;
        cin>>a;
        int t;
        cin>>t;
        for (float j = 1; j <= t; j++) {
            arr[(int)(j * a)] = !arr[(int)(j * a)];
        }
    }
    for (int i = 1; ; i++) {
        if (arr[i] == 1) {
            cout<<i;
            break;
        }
    }

}