#include <bits/stdc++.h>
using namespace std;
#define int ll
typedef unsigned 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);
}
vi d, b;
void calc(int x1, int x2, int y1, int y2, int ind){
int t = d[ind], y = 0, Y = 0;
if (y1/t == y2/t){
if (y1%(2*t)<t)
y = y2-y1+1;
Y = y2-y1+1-y;
} else {
bool k1 = 0;
if (y1%(2*t)<t){
k1 = 1;
y = t-(y1%t);
}
bool k2 = 0;
if (y2%(2*t)<t){
k2 = 1;
y += (y2%t)+1;
}
y += t * ((y2/t - y1/t - 1) / 2);
if (!k1 && !k2)
y += t;
Y = y2-y1+1-y;
}
int x = 0, X = 0;
if (x1/t == x2/t){
if (x1 % (2*t) < t)
x = x2-x1+1;
X = x2-x1+1-x;
} else {
bool k1 = 0;
if (x1%(2*t)<t){
k1 = 1;
x = t-x1%t;
}
bool k2 = 0;
if (x2%(2*t)<t){
k2 = 1;
x += x2%t+1;
}
x += t * ((x2/t - x1/t - 1) / 2);
if (!k1 && !k2)
x += t;
X = x2-x1+1-x;
}
//cout << x << ' ' << y << ' ' << X << ' ' << Y << '\n';
b[ind] += x * y + X*Y;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cerr.tie(nullptr);
int n, k;
cin >> n >> k;
for (int i = 1; i < n; ++i){
if (n % i == 0){
d.push_back(i);
}
}
int len = d.size(), s = 0;
b = vi(len);
for (int i = 0; i < k; ++i){
int x1,y1,x2,y2;
cin >> x1>>y1>>x2>>y2;
--x1;
--y1;
--x2;
--y2;
s += (x2-x1+1) * (y2-y1+1);
for (int j = 0; j < len; ++j)
calc(x1,x2,y1,y2,j);
}
int sol = n*n;
for (int i = 0; i < len; ++i){
//cout << b[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 = s-b[i] + c-b[i];
//cout << c << ' ';
sol = min(sol, res);
b[i] = s-b[i];
c = n*n-c;
res = s+c - 2 * b[i];
//cout << c << endl;
//cout << res << '\n';
sol = min(sol, res);
}
cout << sol << '\n';
}
