#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 1e5+5;
int N, K;
struct Rect
{
int x1, y1, x2, y2;
};
vector<Rect> recs;
bool isWhite(int r, int c, int sz) {
r /= sz;
c /= sz;
return (r+c) % 2 == 0;
}
ll solve(int sz) {
ll res = 0;
ll num = N/sz;
if (num % 2 == 0) {
res = 1LL*N*N/2;
}
else {
res = (1LL*sz*sz) * (1LL*N*N) / 2;
}
//cout << sz << ": " << res << '\n';
for (Rect r: recs) {
if (isWhite(r.x1,r.y1,sz)) {
res++;
}
else {
res--;
}
}
return res;
}
ll solve2(int sz) {
ll res = 0;
ll num = N/sz;
if (num % 2 == 0) {
res = 1LL*N*N/2;
}
else {
res = (1LL*sz*sz) * (1LL*N*N+1) / 2;
}
for (Rect r: recs) {
if (!isWhite(r.x1,r.y1,sz)) {
res++;
}
else {
res--;
}
}
return res;
}
int main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> N >> K;
for (int i = 0; i < K; i++) {
int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
x1--;
y1--;
x2--;
y2--;
recs.push_back({x1,y1,x2,y2});
}
ll ans = 1LL*N*N;
for (int sz = 1; sz < N; sz++) {
if (N % sz == 0) {
ans = min(ans,solve(sz));
ans = min(ans,solve2(sz));
}
}
cout << ans << '\n';
}
