#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 1e6 + 6;
int v[N];
int main() {
int n, k;
cin >> n >> k;
while(k--) {
int a, b;
cin >> a >> b;
v[a - 1] ++, v[b] --;
}
for (int i = 1; i < n; i ++ ) {
v[i] += v[i - 1];
}
sort(v, v + n);
cout << v[n / 2];
return 0;
}