#include<bits/stdc++.h>
#define IOS ios_base::sync_with_stdio(false);cin.tie();cout.tie();
#define aint(x) x.begin(), x.end()
#define int long long
#define pq priority_queue
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define pp pop_back
#define F first
#define S second
using namespace std;
vector<int> di = {1};
int dif[200005];
int find(int x, int d){
return x / (2 * d) * d + min(x % (2 * d), d);
}
void solve () {
int n, k; cin >> n >> k;
for (int i = 2; i * i <= n; i++) {
if (n % i != 0) continue ;
di.pb(i);
if (i * i != n) di.pb(n / i);
}
for (int i = 0; i < di.size(); i++)
dif[i] = n * n - n * n / (di[i] * di[i]) / 2 * (di[i] * di[i]);
int ox, oy, ex, ey;
while (k--) {
int x1, x2, y1, y2; cin >> x1 >> y1 >> x2 >> y2; x1--; y1--;
for (int i = 0; i < di.size(); i++){
ex = find(x2, di[i]) - find(x1, di[i]);
ox = x2 - x1 - ex;
ey = find(y2, di[i]) - find(y1, di[i]);
oy = y2 - y1 - ey;
dif[i] += ex * oy + ey * ox - ex * ey - ox * oy;
}
}
int ans = 1e12;
for (int i = 0; i < di.size(); i++) ans = min(ans, min(dif[i], n * n - dif[i]));
cout << ans;
}
signed main() {IOS solve(); return 0;}
