//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#define ll long long
#define maxn 100005
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
struct rect{
ll x1, y1, x2, y2;
rect() {
x1 = 0, y1 = 0, x2 = 0, y2 = 0;
}
rect(int a, int b, int c, int d) {
x1 = a, y1 = b, x2 = c, y2 = d;
}
};
vector<rect> v;
inline ll wnum(ll x, ll y, ll len) {
if (x < 0 || y < 0) return 0;
ll ret = 0;
ll cx = x / len, cy = y / len;
ll lx = x % len, ly = y % len;
if (cx % 2 == 0 || cy % 2 == 0) {
ret += len * len * (cx * cy / 2);
} else {
ret += len * len * ((cx * cy + 1) / 2);
}
if (cy % 2 == 0) { //white
ret += ly * ((cx + 1) / 2) * len;
} else {
ret += ly * (cx / 2) * len;
}
if (cx % 2 == 0) {
ret += lx * ((cy + 1) / 2) * len;
} else {
ret += lx * (cy / 2) * len;
}
if (((cx + cy) % 2) == 0) ret += lx * ly;
//cout << x << " " << y << " " << len << " " << ret << endl;
return ret;
}
ll solve(ll n, ll len) {
ll val = n * n - wnum(n, n, len);
//cout << len << endl;
for (rect a:v) {
ll wn = wnum(a.x2+1, a.y2+1, len) - wnum(a.x1, a.y2+1, len) - wnum(a.x2+1, a.y1, len) + wnum(a.x1, a.y1, len);
//cout << a.x1 << " " << a.y1 << " " << wn << endl;
val += 2 * wn - (a.x2 - a.x1 + 1) * (a.y2 - a.y1 + 1);
}
val = min(val, n * n - val);
//cout << len << " " << val << endl;
return val;
}
int main() {
io
ll n, k;
cin >> n >> k;
for (int i = 0;i < k;i++) {
ll x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
x1--, y1--, x2--, y2--;
v.push_back(rect(x1, y1, x2, y2));
}
ll ans = 1LL<<60;
for (ll i = 1;i * i <= n;i++) {
if (n % i == 0) {
ans = min(ans, solve(n, i));
if (i * i != n && i != 1) {
ans = min(ans, solve(n, n / i));
}
}
}
cout << ans << endl;
}
/*
2 0
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
4 1
4 1 4 4
*/
