#include <algorithm>
#include <bits/stdc++.h>
#include <cassert>
#include <iomanip>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define ff first
#define ss second
#define ln "\n"
#define mp make_pair
const ll INF = 2e18;
const ll MOD = 1e9+7;
struct rect{
ll si, sj, ti, tj;
ll area(){
return (ti-si+1)*(tj-sj+1);
}
};
ll gencost(ll x, ll n, ll k, vector<rect> &a){
ll asum=0, isum=0;
for (auto rec:a){
asum+=rec.area();
// ll psi = (rec.si/x+(rec.si%x?1:0))*x;
// ll psj = (rec.sj/x+(rec.sj%x?1:0))*x;
// ll pti = (rec.ti/x)*x;
// ll ptj = (rec.tj/x)*x;
if ((rec.si/x+rec.sj/x)%2) isum++;
}
ll bsum = ((n/x)/2)*n*x+((n/x)%2?((n/x/2+1)*x*x):0);
return min(bsum+isum-(asum-isum), (n*n-bsum)+(asum-isum)-isum);
}
void solve(){
ll n, k; cin >> n >> k;
vector<rect> a(k);
for (ll i=0; i<k; i++){
cin >> a[i].si >> a[i].sj >> a[i].ti >> a[i].tj;
a[i].si--; a[i].sj--; a[i].ti--; a[i].tj--;
}
ll cost=INF;
for (ll i=1; i*i<=n; i++){
if (n%i==0){
cost=min(cost, gencost(i, n, k, a));
if(n/i!=n) cost=min(cost, gencost(n/i, n, k, a));
}
}
cout << cost << ln;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
auto start = chrono::high_resolution_clock::now();
ll t=1;
// cin >> t;
while (t--) solve();
#ifdef LOCAL
auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
cout << setprecision(0) << fixed << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
#endif
}
