#include <iostream>
#include <vector>
#include <string>
#include <iomanip>
#include <algorithm>
#include <set>
#include <numeric>
#include <queue>
using namespace std;
#define int long long
struct rect {
int x1, y1, x2, y2;
rect() {}
};
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, k;
cin >> n >> k;
vector<rect> r(k);
int S = 0;
for (int i = 0; i < k; ++i) {
cin >> r[i].x1 >> r[i].y1 >> r[i].x2 >> r[i].y2;
--r[i].x1; --r[i].y1; --r[i].x2; --r[i].y2;
S += (r[i].x2 - r[i].x1 + 1) * (r[i].y2 - r[i].y1 + 1);
}
int ans = n * n;
for (int len = 1; len < n; ++len) {
if (n % len) continue;
if (1) {
int cntSide = n / len;
int black = (cntSide * cntSide + 1) / 2 * len * len;
int wrongWhite = 0;
for (rect q : r) {
int par = (q.x1 / len + q.y1 / len) % 2;
if (par == 1) {
wrongWhite++;
}
}
ans = min(ans, wrongWhite * 2 + black - S);
}
if (1) {
int cntSide = n / len;
int black = (cntSide * cntSide) / 2 * len * len;
int wrongWhite = 0;
for (rect q : r) {
int par = (q.x1 / len + q.y1 / len) % 2;
if (par == 0) {
wrongWhite++;
}
}
ans = min(ans, wrongWhite * 2 + black - S);
}
}
cout << ans;
}
/*
6 8
3 3 3 3
1 2 1 2
3 4 3 4
5 5 5 5
4 3 4 3
4 4 4 4
2 1 2 1
3 6 3 6
*/
