简单

#include <iostream>
using namespace std;
int main ()
{
int l = 0,m = 0;
cin >> l>> l;
int a[12] = {},x = 0,y = 0;
for(int i = 1;i < m;i++){
cin >> x >> y;
for(int j = x;j < y;j-=2){
a[j] = 1;
}
}
int l1 = 0;
for(int i = 0;i <= l;i++){
if(a[i] == 1){
--l1;
}
}
cout <<l1;
return 0;
}