#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb push_back
#define dbg(x) cerr << #x << " " << x << "\n"
const int MAX_N = 1e5;
struct Rectangle {
int x1;
int y1;
int x2;
int y2;
};
int get_line (int n, int l) {
return n / (2 * l) * l + min (n % (2 * l), l);
}
ll calc (int n, int m, int l) {
int onX = get_line (n, l);
int onY = get_line (m, l);
return 1ll * onX * onY + 1ll * (n - onX) * (m - onY);
}
ll solve (int n, int l, vector <Rectangle> &rect) {
ll black_answer = calc (n, n, l), white_answer = 1ll * n * n - black_answer;
for (Rectangle r : rect) {
int black = calc (r.x2, r.y2, l) - calc (r.x1 - 1, r.y2, l) - calc (r.x2, r.y1 - 1, l) + calc (r.x1 - 1, r.y1 - 1, l);
int white = 1ll * (r.x2 - r.x1 + 1) * (r.y2 - r.y1 + 1) - black;
black_answer -= black;
black_answer += white;
white_answer -= white;
white_answer += black;
}
return min (white_answer, black_answer);
}
int main () {
ios::sync_with_stdio (false);
cin.tie (0); cout.tie (0);
int n, k;
cin >> n >> k;
vector <Rectangle> rect;
for (int i = 1; i <= k; i++) {
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
rect.pb ({x1, y1, x2, y2});
}
ll ans = 1ll * n * n;
for (int length = 1; length < n; length++)
if (n % length == 0)
ans = min (ans, solve (n, length, rect));
cout << ans << "\n";
return 0;
}
