#include <bits/stdc++.h>
#define pii pair<ll, ll>
#define X first
#define Y second
#define ll long long
using namespace std;
const int N = 2 * 1e5 + 10;
const ll INF = 1e12;
ll n, m, d;
pii rect[N][4];
bool b;
bool getCol(ll x, ll y){
if(((x & 1) == (y & 1))) return b;
return !b;
}
ll rectangle(ll x, ll y){
ll ret = ((x * y) / 2) * d * d;
if((x & 1) && (y & 1))
ret += b ? d * d : 0;
return ret;
}
ll area(ll x, ll y){
if((x & 1) && (y & 1)){
if(b) return -(d * d);
else return d * d;
}
return 0;
}
ll calcPart(ll w, ll h, bool col){
if(col){
return (h & 1) ? -(w * d) : 0;
}
return (h & 1) ? w * d : 0;
}
ll pref(pii p){
ll x = p.X;
ll y = p.Y;
ll lenx = x / d, leny = y / d;
ll ret = area(lenx, leny);
x = x % d;
y = y % d;
if(getCol(lenx, leny)) ret -= x * y;
else ret += x * y;
ret += calcPart(x, leny, getCol(lenx, 0));
ret += calcPart(y, lenx, getCol(0, leny));
return ret;
}
int main(){
scanf("%lld%d", &n, &m);
for(int i = 0; i < m; i++){
ll x, y, x2, y2;
scanf("%lld%lld%lld%lld", &x, &y, &x2, &y2);
rect[i][0] = {x2, y2};
rect[i][2] = {x - 1, y - 1};
rect[i][1] = {x - 1 , y2};
rect[i][3] = {x2, y - 1};
}
ll ans = INF;
for(int i = 1; i < n; i++){
if(n % i) continue;
d = i;
for(int nb = 0; nb < 2; nb++){
b = nb;
ll res = rectangle(n / d, n / d);
for(int j = 0; j < m; j++){
res += pref(rect[j][0]) - pref(rect[j][1]) + pref(rect[j][2]) - pref(rect[j][3]);
// if(i == 5) cout << pref(rect[j][0]) - pref(rect[j][1]) + pref(rect[j][2]) - pref(rect[j][3]) << " +\n";
}
// printf("%d %d %d %d\n", i, nb, rectangle(n / d, n / d), res);
ans = min(ans, res);
}
}
cout << ans << "\n";
return 0;
}
