#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <iomanip>
#include <stack>
#include <queue>
#include <deque>
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define pb push_back
#define ppb pop_back
#define mkp make_pair
#define F first
#define S second
#define show(a) cerr << #a <<" -> "<< a <<"\n"
#define fo(a, b, c, d) for(int (a) = (b); (a) <= (c); (a) += (d))
#define foo(a, b, c ,d) for(int (a) = (b); (a) >= (c); (a) -= (d))
//#define int ll
const int N = 2000;
const int INF = 2e9 + 5;
int sc[N][N];
void solve1(int n, int k) {
for(int it = 1; it <= k; ++it) {
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
//swap(x1, y1);
//swap(x2, y2);
for(int i = x1; i <= x2; ++i) {
++sc[i][y1];
}
for(int i = x1; i <= x2; ++i) {
--sc[i][y2 + 1];
}
}
vector <int> d;
d.pb(1);
for(int i = 2; i * i <= n; ++i) {
if(n % i == 0) {
d.pb(i);
if(i != n / i) d.pb(n / i);
}
}
int ans = INF;
for(int di : d) {
int res1 = 0, res2 = 0;
for(int i = 1; i <= n; ++i) {
int cur = 0;
bool vs = ((((i - 1) / di) & 1) ^ 1);
for(int j = 1; j <= n; ++j) {
cur += sc[i][j];
// (cur > 0) -> black : white
if(cur > 0) {
if((((j - 1) / di) & 1) ^ vs) ++res1;
else ++ res2;
} else {
if((((j - 1) / di) & 1) ^ vs) ++res2;
else ++res1;
}
}
}
/*for(int i = 1; i <= n; ++i) {
bool vs = ((((i - 1) / di) & 1) ^ 1);
for(int j = 1; j <= n; ++j) {
if((((j - 1) / di) & 1) ^ vs) cout << 1;
else cout << 2;
}
cout << '\n';
}
cout << '\n';*/
ans = min(ans, min(res1, res2));
}
cout << ans;
}
/*void solve2(int n, int k) {
}*/
int main () {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, k;
cin >> n >> k;
//if(n <= 1000) {
solve1(n, k);
//} else {
// solve2(n, k);
//}
return 0;
}
/*
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
4 1
4 1 4 4
If you only do what you can do,
You will never be more than you are now!
*/
