#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
using ll = long long;
vector<ll> dv;
vector<pair<int, int>> points;
ll ans;
int main()
{
ll n, k;
cin >> n >> k;
ans = n * n;
for (int i = 1; i < n; i++)
if (n % i == 0)dv.push_back(i);
for (int i = 0; i < k; i++)
{
int a, b, c, d;
cin >> a >> b >> c >> d;
for (int x = a; x <= c; x++)
for (int y = b; y <= d; y++)
points.push_back({ x,y });
}/*
for (auto p : points)
cerr << p.first << ' ' << p.second << '\n';*/
for (ll d : dv)
{
ll blackans;
ll q = n / d;
if (q % 2)
blackans = (n * n - d * d) / 2 + d * d;
else blackans = n * n / 2;
ll whiteans = n * n - blackans;
//cerr << blackans << ' ' << whiteans << '\n';
for (auto p : points)
{
int x = p.first, y = p.second;
if ((((x + d - 1) / d) % 2) == (((y + d - 1) / d) % 2))
{
//cout << "!!" << x << ' ' << y << '\n';
blackans--;
whiteans++;
}
else
{
blackans++;
whiteans--;
}
}
ans = min(ans, min(blackans, whiteans));
//if (d == 2)
// cout << blackans << ' ' << whiteans << '\n';
}
cout << ans;
return 0;
}
