#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define ll long long
#define jaldi_kar() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
void samadhan(){
int n , k;
cin >> n >> k;
map<int , vector<int>> m;
while(k--){
int a , b;
cin >> a >> b;
m[a].push_back(b);
}
for(auto p : m){
sort(p.second.begin() , p.second.end());
}
vector<int> res(n);
for(int i=1;i<=n;i++){
for(auto p : m){
if(p.first > i) break;
auto it = lower_bound(p.second.begin() , p.second.end() , i);
res[i-1] += (p.second.end() - it);
}
}
sort(res.begin() , res.end());
cout << res[n/2] <<"\n";
}
int main()
{
jaldi_kar();
ll t;
t = 1;
for(int it=1;it<=t;it++) {
samadhan();
}
return 0;
}
