#include<bits/stdc++.h>
using namespace std;
int h[2000010], n, t;
double a;
int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a >> t;
		int g = a;
		for (int j = 1; j <= t; j++) {
			if (h[g * j] == 1) {
				h[g * j] = 0;
			} else {
				h[g * j] = 1;
			}
		}
	}
	for (int i = 1; i <= 2000000; i++) {
		if (h[i] == 1) {
			cout << i;
			return 0;//exit(0);
		}
	}
	return 0;
}

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