#include<iostream>
using namespace std;
#include<cstring>
int main()
{
int l,m;
cin>>l>>m;
int count=0;
int arr[10000]={0};
for (int i = 0; i <= l; i++)
{
arr[i] = { 0 };
}
for(int i=0;i<m;i++)
{
int start,end;
cin>>start>>end;
for(int j=start;j<=end;j++)
{
if(arr[j]==0)
arr[j]=1;
}
}
for(int i=0;i<=l;i++)
{
if(arr[i]==0)
count++;
}
cout<<count;
return 0;
}
```cpp
```
by jingshenshiliang @ 2023-11-08 22:06:58
这是代码，第一回发帖，不太熟练，望谅解
by jingshenshiliang @ 2023-11-08 22:08:02