View Code of Problem 2346

#include<stdio.h>
#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<stack>
#include<map>
#include<vector>
using namespace std;


int main()
{
	int a, b;
	while(cin >> a >> b){
		if (a == 0 && b == 0) {
			break;
		}
	int p[10001] = { 0 };
	for (int i = 0; i < b; i++) {
		int nice, big;
		cin >> nice >> big;
		if (nice > big) {
			int t = nice;
			nice = big;
			big = t;
		}
		for (int y = nice; y <= big; y++) {
			p[y] = 1;
		}
	}
	int sum = 0;
	for (int z = 0; z <= a; z++) {
		if (p[z] == 1) {
			sum++;
		}
	}
	cout << a + 1 - sum << endl;
	}
	return 0;
}