#include <bits/stdc++.h>
using namespace std;
#define int ll
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<pi> vp;
typedef vector<pl> vpl;
void no(){
cout << "-1\n";
exit(0);
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cerr.tie(nullptr);
int n, k;
cin >> n >> k;
vi d;
for (int i = 1; i < n; ++i){
if (n % i == 0){
d.push_back(i);
}
}
int len = d.size();
vi b(len);
for (int i = 0; i < k; ++i){
int x1,y1,x2,y2;
cin >> x1>>y1>>x2>>y2;
if (x1!=x2 || y1 != y2)
return 0;
--x1;
--y1;
for (int j = 0; j < len; ++j){
int t = d[j];
bool b1 = (x1%(2*t) < t), b2 = (y1%(2*t) < t);
if (b1 == b2){
b[j]++;
}
}
}
int sol = n*n;
for (int i = 0; i < len; ++i){
int t = d[i],c;
if (n % (2*t) == 0)
c = (n*n)/2;
else
c = ((n-t)*(n-t))/2 + n*t;
int res = k-b[i] + c-b[i];
//cout << c << ' ';
sol = min(sol, res);
b[i] = k-b[i];
c = n*n-c;
res = k+c - 2 * b[i];
//cout << c << endl;
sol = min(sol, res);
}
cout << sol << '\n';
}
