#include <bits/stdc++.h>
using namespace std;
#define int long long
const int NM = 1e5, inf = 1e18;
int N, K, x[NM+5], y[NM+5], u[NM+5], v[NM+5], ans = +inf;
int num[2];
void update(int lx, int ly, int rx, int ry, int c){
if (lx > rx) return;
if (ly > ry) return;
int tmp = (rx-lx+1)*(ry-ly+1);
num[(lx+ly)&1] += (tmp+1)/2 * c;
num[!((lx+ly)&1)] += tmp/2 * c;
}
void solve(int t){
num[0] = num[1] = 0;
for (int i = 1; i <= K; i++){
int blx = x[i]/t+(x[i]%t > 0), bly = y[i]/t+(y[i]%t > 0), blu = u[i]/t+(u[i]%t > 0), blv = v[i]/t+(v[i]%t > 0);
if (blx == blu && bly == blv) update(blx, bly, blx, bly, (u[i]-x[i]+1)*(v[i]-y[i]+1));
else if (blx == blu){
update(blx, bly, blx, bly, (u[i]-x[i]+1)*(bly*t-y[i]+1));
update(blx, blv, blx, blv, (u[i]-x[i]+1)*(v[i]-(blv-1)*t));
update(blx, bly+1, blx, blv-1, (u[i]-x[i]+1)*t);
}
else if (bly == blv){
update(blx, bly, blx, bly, (blx*t-x[i]+1)*(v[i]-y[i]+1));
update(blu, bly, blu, bly, (u[i]-(blu-1)*t)*(v[i]-y[i]+1));
update(blx+1, bly, blu-1, bly, t*(v[i]-y[i]+1));
}
else{
update(blx, bly, blx, bly, (blx*t-x[i]+1)*(bly*t-y[i]+1));
update(blx, blv, blx, blv, (blx*t-x[i]+1)*(v[i]-(blv-1)*t));
update(blu, bly, blu, bly, (u[i]-(blu-1)*t)*(bly*t-y[i]+1));
update(blu, blv, blu, blv, (u[i]-(blu-1)*t)*(v[i]-(blv-1)*t));
update(blx, bly+1, blx, blv-1, (blx*t-x[i]+1)*t);
update(blx+1, bly, blu-1, bly, t*(bly*t-y[i]+1));
update(blu, bly+1, blu, blv-1, (u[i]-(blu-1)*t)*t);
update(blx+1, blv, blu-1, blv, t*(v[i]-(blv-1)*t));
update(blx+1, bly+1, blu-1, blv-1, t*t);
}
}
int targ = t*t*(N*N/(t*t)/2);
ans = min(ans, abs(targ-num[1])+num[0]);
ans = min(ans, abs(N*N-targ-num[0])+num[1]);
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N >> K;
for (int i = 1; i <= K; i++){
cin >> x[i] >> y[i] >> u[i] >> v[i];
}
for (int i = 1; i*i <= N; i++)
if (N%i == 0){
solve(i);
if (i > 1) solve(N/i);
}
cout << ans;
return 0;
}
