import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long a = 0;
		long b = 0;
		for (int i = 1; i < n; i++) {
		    a += sc.nextInt();
		    b += sc.nextInt();
		}
		System.out.println(Math.min(a, b) + 1);
	}
}