2563 : 색종이

import java.util.Scanner;

public class Main2 {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int num = sc.nextInt();
		int[][] area = new int[100][100];
		int cnt = 0;

		for (int i = 0; i < num; i++) {

			int area1 = sc.nextInt(); // 열 우선 입력
			int area2 = sc.nextInt(); // 행 입력

			for (int j = area1; j < area1 + 10; j++) {
				for (int k = area2; k < area2 + 10; k++) {
					if (area[j][k] == 1)
						continue;
					area[j][k] = 1;
					cnt++;
				}
			}
		}
		System.out.println(cnt);
	}
}