//Dost SEFEROĞLU
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define sp << " " <<
#define vi vector<int>
#define all(xx) xx.begin(),xx.end()
#define ps(xxx) cout << (xxx) << endl;
const int N = 5e2+1,inf = 1e16,MOD = 1e9+7;
struct ST {
vector<pii> t;
vi lazy;
void build(int node,int l,int r) {
if (l == r) {
t[node] = {0,1};
return;
}
int m = (l+r) >> 1;
build(2*node,l,m),build(2*node+1,m+1,r);
t[node].ff = 0;
t[node].ss = t[2*node].ss+t[2*node+1].ss;
}
ST(int nn) {
t.resize(4*nn+1);
build(1,1,nn);
lazy.assign(4*nn+1,0);
}
void push(int node,bool leaf) {
if (!lazy[node]) return;
t[node].ff = t[node].ss-t[node].ff;
if (!leaf) {
lazy[2*node]^=1;
lazy[2*node+1]^=1;
}
lazy[node] = 0;
}
void update(int node,int l,int r,int L,int R) {
push(node,l==r);
if (l > R || r < L) return;
if (l >= L && r <= R) {
lazy[node]^=1;
push(node,l==r);
return;
}
int m = (l+r) >> 1;
update(2*node,l,m,L,R),update(2*node+1,m+1,r,L,R);
t[node].ff = t[2*node].ff+t[2*node+1].ff;
}
int query(int node,int l,int r,int L,int R) {
push(node,l==r);
if (l > R || r < L) return 0;
if (l >= L && r <= R) return t[node].ff;
int m = (l+r) >> 1;
return query(2*node,l,m,L,R)+query(2*node+1,m+1,r,L,R);
}
void clear(int nn) {
lazy.assign(4*nn+1,0);
for (auto& it : t) it.ff = 0;
}
};
void solve() {
int n,k;
cin >> n >> k;
vector<pii> upds[n+1];
for (int i=1;i<=k;i++) {
int x1,y1,x2,y2;
cin >> x1 >> y1 >> x2 >> y2;
upds[x1].push_back({y1,y2});
if (x2 < n) upds[x2+1].push_back({y1,y2});
}
vi divs;
for (int i=1;i<n;i++) if (n%i == 0) divs.push_back(i);
int ans = inf;
ST st1(n),st2(n);
for (int d : divs) {
st1.clear(n);
st2.clear(n);
int cur = 1;
while (cur <= n) {
if ((cur/d)%2) st2.update(1,1,n,cur,cur+d-1);
else st1.update(1,1,n,cur,cur+d-1);
cur+=d;
}
int need = 0;
for (int j = 1;j<=n;j++) {
for (auto it : upds[j]) {
st1.update(1,1,n,it.ff,it.ss);
st2.update(1,1,n,it.ff,it.ss);
}
if (((j-1)/d)%2 == 0) need+=st1.query(1,1,n,1,n);
else need+=st2.query(1,1,n,1,n);
}
ans = min(ans,need);
ans = min(ans,n*n-need);
}
cout << ans << endl;
}
signed main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#ifdef Dodi
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
