/*
Code written by Talant I.D.
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
#define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
inline bool isvowel(char ch){
ch = tolower(ch);
return (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u');
}
inline bool isprime(int n){
if(n < 2 || (n%2 == 0 && n != 2)) return false;
for(int i = 3; i*i <= n; i++)
if(n%i == 0) return false;
return true;
}
class Union{
private:
vector <int> saizu, link;
public:
Union(int n){
saizu.assign(n, 1); link.resize(n);
iota(all(link), 0);
}
int find(int n){
if(link[n] == n) return n;
return link[n] = find(link[n]);
}
int same(int a, int b){
return find(a) == find(b);
}
void unite(int a, int b){
if(same(a, b)) return;
a = find(a); b = find(b);
if(saizu[a] < saizu[b]) swap(a, b);
saizu[a] += saizu[b];
link[b] = a;
}
int getsize(int a){
return saizu[find(a)];
}
};
const int mod = 1e9+7;
ll mode(ll a){
a %= mod;
if(a < 0) a += mod;
return a;
}
ll subt(ll a, ll b){
return mode(mode(a)-mode(b));
}
ll add(ll a, ll b){
return mode(mode(a)+mode(b));
}
ll mult(ll a, ll b){
return mode(mode(a)*mode(b));
}
ll binpow(ll a, ll b){
ll res = 1;
while(b){
if(b&1) res = mult(res, a);
a = mult(a, a);
b >>= 1;
}
return res;
}
int main(){
do_not_disturb
ll n, k, ans = 9e18;
cin >> n >> k;
ll x1[k], y1[k], x2[k], y2[k];
for(ll i = 0; i < k; i++){
cin >> x1[i] >> y1[i] >> x2[i] >> y2[i];
x1[i]--; y1[i]--; x2[i]--; y2[i]--;
}
for(ll i = 1; i*i <= n; i++){
if(n%i == 0){
ll to_white = 0, to_black = ((n*n/i/i)&1 ? (n*n/i/i/2+1)*i*i : (n*n/2));
for(ll j = 0; j < k; j++){
for(ll w = x1[j]; w <= x2[j]; w++){
for(ll o = y1[j]; o <= y2[j]; o++){
ll cnt = w/i+o/i;
if(cnt%2 == 0){
to_black--;
}
else{
to_white++;
}
}
}
}
ans = min(ans, to_black+to_white);
to_white = 0, to_black = (n*n/i/i/2);
to_black *= i*i;
for(ll j = 0; j < k; j++){
for(ll w = x1[j]; w <= x2[j]; w++){
for(ll o = y1[j]; o <= y2[j]; o++){
ll cnt = w/i+o/i;
if(cnt%2 == 0){
to_white++;
}
else{
to_black--;
}
}
}
}
ans = min(ans, to_black+to_white);
if(i == 1) continue;
ll q = i;
i = n/i;
to_white = 0, to_black = ((n*n/i/i)&1 ? (n*n/i/i/2+1)*i*i : (n*n/2));
for(ll j = 0; j < k; j++){
for(ll w = x1[j]; w <= x2[j]; w++){
for(ll o = y1[j]; o <= y2[j]; o++){
ll cnt = w/i+o/i;
if(cnt%2 == 0){
to_black--;
}
else{
to_white++;
}
}
}
}
ans = min(ans, to_black+to_white);
to_white = 0, to_black = (n*n/i/i/2);
to_black *= i*i;
for(ll j = 0; j < k; j++){
for(ll w = x1[j]; w <= x2[j]; w++){
for(ll o = y1[j]; o <= y2[j]; o++){
ll cnt = w/i+o/i;
if(cnt%2 == 0){
to_white++;
}
else{
to_black--;
}
}
}
}
ans = min(ans, to_black+to_white);
i = q;
}
}
cout << ans << endl;
return 0;
}
