#include <bits/stdc++.h>
#define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<char,char> pcc;
typedef pair<pii,int> ipii;
typedef pair<pii,pii> ipiii;
const int MAXN = 2e5+10;
const int MAXA = 1e7+10;
const int INF = 1e18+10;
const int SQRT = 300;
const int LOG = 20;
const ld EPS = 1e-6;
const int MOD = 998244353;
int sum(int a, int b){ return (a+b)%MOD; }
void chsum(int &a, int b){ a = (a+b)%MOD; }
void chsub(int &a, int b){ a = (a+MOD-b)%MOD; }
int mul(int a, int b){ return (a*b)%MOD; }
void chmul(int &a, int b){ a = (a*b)%MOD; }
void chmn(int &a, int b){ a = min(a, b); }
void chmx(int &a, int b){ a = max(a, b); }
int n, m, a[MAXN][5];
int ans = INF, siz;
int bl = 0, wh = 0;
void tot(int x, int y, int ty){
if(x==-1 || y==-1) return;
int r = x/siz, c = y/siz;
if((r+c)%2 == 0) bl += ty * (x-r*siz) * (y-c*siz);
else wh += ty * (x-r*siz) * (y-c*siz);
int p = ty * (y-c*siz) * siz * ((r+1)/2), q = ty * (y-c*siz) * siz * (r/2);
if(c%2 == 0) bl += p, wh += q;
else bl += q, wh += p;
p = ty * (x-r*siz) * siz * ((c+1)/2), q = ty * (x-r*siz) * siz * (c/2);
if(r%2 == 0) bl += p, wh += q;
else bl += q, wh += p;
p = ty * siz * siz * ((r*c+1)/2), q = ty * siz * siz * ((r*c)/2);
bl += p; wh += q;
}
void cnt(){
bl = 0; wh = 0;
for(int i=1; i<=m; i++){
tot(a[i][3], a[i][4], 1);
tot(a[i][1]-1, a[i][2]-1, 1);
tot(a[i][3], a[i][2]-1, -1);
tot(a[i][1]-1, a[i][4], -1);
}
// cout << siz << ' ' << bl << ' ' << wh << " wh\n";
int blcell = ((n/siz)*(n/siz)+1)/2; blcell *= siz*siz;
int whcell = (n/siz)*(n/siz)/2; whcell *= siz*siz;
chmn(ans, blcell -bl+wh);
chmn(ans, whcell -wh+bl);
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>n>>m;
for(int i=1; i<=m; i++){
cin>>a[i][1] >> a[i][2]>>a[i][3]>>a[i][4];
}
for(int ss=1; ss<n; ss++){
if(n%ss==0){
siz = ss;
cnt();
}
}
cout << ans << '\n';
}
