import java.math.BigDecimal;
import java.util.HashSet;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int inputLineNum = scanner.nextInt();
        HashSet<Integer> opens = new HashSet<>();//写外面不符合原思路，怎么办？
        for (int count = 0; count < inputLineNum; count++) {
            BigDecimal a = new BigDecimal(scanner.next());
            int t = scanner.nextInt();
            //开灯的记下来，关灯的不记
            for (int left = 1; left <= t; left++) {
                int k = a.multiply(BigDecimal.valueOf(left)).intValue();
                if (opens.contains(k))
                    opens.remove(k);
                else
                    opens.add(k);
            }
        }
        System.out.println(opens.iterator().next());
    }
}

就挺意外的QwQ