0分求助，例子和下载的样例一都对，但就是一个不过

就输出一个数字也应该不会全WA啊

#include <iostream>

using namespace std;

int main() {
    int n, times, count;

    cin >> n >> times;
    int arr[n + 1] = {0};

    for (int i = 0; i < times; i++) {
        int a = 0;
        int b = 0;
        cin >> a >> b;
        for (int j = a; j <= b; j++) {
            arr[j] = 1;
        }
    }

    for (int i = 0; i < n + 1; i++) {
        if (arr[i] == 0)
            count++;
    }
    cout << count;

}