#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
ll N,K,ans;
vector<pair<pi,pi>> v;
ll solve(int x, int y, int len) {
int X = x%(2*len), Y = y%(2*len);
// suppose bottom left square is black
ll z = (x/(2*len))*len;
z += min(X,len);
ll res = (ll)(y/(2*len))*len*x;
res += min(Y,len)*z;
res += max(Y-len,0)*(x-z);
return res;
}
ll correct(pair<pi,pi> a, int len) {
return solve(a.f.s,a.s.s,len)-solve(a.f.f-1,a.s.s,len)-solve(a.f.s,a.s.f-1,len)+solve(a.f.f-1,a.s.f-1,len);
}
ll area(pair<pi,pi> a) {
return (ll)(a.f.s-a.f.f+1)*(a.s.s-a.s.f+1);
}
ll solve(int len) {
ll ans = N*N-correct({{1,N},{1,N}},len);
for (auto a: v) {
ll x = correct(a,len);
ans -= (area(a)-x);
ans += x;
}
return ans;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> K;
F0R(i,K) {
pair<pi,pi> t; cin >> t.f.f >> t.s.f >> t.f.s >> t.s.s;
v.pb(t);
}
FOR(i,1,N) if (N % i == 0) {
ll t = solve(i);
t = max(t,N*N-t);
ans = max(ans,t);
}
cout << N*N-ans;
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
