#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define ll long long
#define ld long double
#define pii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define prc(n) fixed << setprecision(n)
#define fastios ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pi acos(-1);
const int inf = 1e9+7;
const int N = 1e3+5;
vector<pii>v;
int x[N][N];
ll ans, n, k;
void check(int rem){
int cnt = 0;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
if((j + i)%2 == rem && !x[i][j]) cnt++;
else if((i+j) % 2 != rem && x[i][j]) cnt++;
}
}
ans = min((ll)cnt, ans);
}
void solve(){
fastios
ans = inf;
cin>>n>>k;
if(k == 0){
ans = n*n/2;
for(int i=2;i*1ll*i<=n;i++){
if(n % i == 0){
ll num = n/i;
ans = min(ans, num * num /2 * i * i);
num = i;
ans = min(ans, num * num /2 * (n/i) * (n/i));
}
}
cout<<ans<<"\n";
return;
}
for(int i=0;i<k;i++){
int a, b, c, d;
cin>>a>>b>>c>>d;
x[--a][--b] = 1;
}
check(1);
check(0);
cout<<ans;
return;
}
/*
3 3
1 3 1 3
2 3 3 3
1 1 3 1
5 8
2 1 2 1
3 1 3 1
5 2 5 2
1 5 1 5
2 3 2 3
2 4 2 4
3 3 3 3
4 3 4 3
*/
int main(){
fastios
int t = 1;
//cin>>t;
while(t--) solve();
return 0;
}
