#include <iostream>
#define int long long int
#define ericxiao ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
const int maxN = 1e5 + 326;
struct Rect{
int l, r, d, u, A;
Rect(){}
Rect(int l, int r, int d, int u): l(l), r(r), d(d), u(u){
A = (r - l + 1) * (u - d + 1);
}
} rects[maxN];
inline bool onDiag(int x, int y, int d){
return (((x % (2 * d)) < d) == ((y % (2 * d)) < d));
}
inline int id(int x, int y, int d){
return x / d * maxN + y / d;
}
int N, K;
inline int check(int d){
//top left is black
//cout << "d = " << d << endl;
int _ans = maxN * maxN, tmp = ((N / d) * (N / d) + 1) / 2 * (d * d);
//cout << "1tmp = " << tmp << endl;
for(int i = 0; i < K; i++){
if(id(rects[i].l, rects[i].u, d) == id(rects[i].r, rects[i].d, d)){
//cout << onDiag(rects[i].l, rects[i].u, d) && onDiag(rects[i].r, rects[i].d, d);
if(onDiag(rects[i].l, rects[i].u, d) && onDiag(rects[i].r, rects[i].d, d)) tmp -= rects[i].A;
else tmp += rects[i].A;
} else {
tmp = maxN * maxN;
break;
}
}
cout << endl;
//cout << "1: " << tmp << endl;
_ans = min(_ans, tmp);
tmp = ((N / d) * (N / d)) / 2 * (d * d);
for(int i = 0; i < K; i++){
if(id(rects[i].l, rects[i].u, d) == id(rects[i].r, rects[i].d, d)){
if(onDiag(rects[i].l, rects[i].u, d) && onDiag(rects[i].r, rects[i].d, d)) tmp += rects[i].A;
else tmp -= rects[i].A;
} else {
tmp = maxN * maxN;
break;
}
}
//cout << "2: " << tmp << endl;
_ans = min(_ans, tmp);
//cout << "d = " << d << ", ans = " << _ans << endl;
return _ans;
//top right is black
}
signed main(){
ericxiao;
cin >> N >> K;
int l, r, d, u;
for(int i = 0; i < K; i++){
cin >> l >> d >> r >> u;
l--; d--; r--; u--;
rects[i] = Rect(l, r, d, u);
//cout << "rects[i] a = " << rects[i].A << endl;
}
int ans = maxN * maxN;
for(int div = 1; div * div <= N; div++){
if(!(N % div)){
ans = min(ans, check(div));
if(div != 1) ans = min(ans, check(N / div));
}
}
cout << ans << endl;
}
/*
*
6 8
3 3 3 3
1 2 1 2
3 4 3 4
5 5 5 5
4 3 4 3
4 4 4 4
2 1 2 1
3 6 3 6
*/
