题目1088：剩下的树

import java.io.IOException;import java.io.FileReader;import java.io.BufferedReader;import java.util.Scanner;import java.util.Vector;class Main {public static final boolean DEBUG = false;public static void main(String[] args) throws IOException{Scanner cin;int l, m;if (DEBUG) {cin = new Scanner(new BufferedReader(new FileReader("d:\\OJ\\uva_in.txt")));} else {cin = new Scanner(System.in);}while (cin.hasNext()) {l = cin.nextInt();m = cin.nextInt();boolean[] vis = new boolean[l + 1];int cnt = 0;while (m-- > 0) {int a, b;a = cin.nextInt();b = cin.nextInt();if (a > b) {int tmp = a;a = b;b = tmp;}for (int i = a; i <= b; i++) {if (!vis[i]) {cnt++;vis[i] = true;}}}System.out.println(l + 1 - cnt);}}}