#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
#define pb push_back
#define popf pop_front
#define popb pop_back
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if (str != "") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
vector<pair<pair< long long, long long>, pair< long long, long long>>> points;
long long ansi = 1e17;
vector<long long> get_divisors(long long n) {
vector<long long> answ{1};
for(long long i = 2; i * i <= n; i++) {
if(n % i == 0) {
answ.push_back(i);
if(n / i != i) {
answ.push_back(n / i);
}
}
}
return answ;
}
long long n, k;
void check(long long curr) {
long long first = 0, second = 0;
for(auto i: points) {
long long x1 = i.first.first - 1, y1 = i.first.second - 1;
long long x2 = i.second.first - 1, y2 = i.second.second - 1;
// y1 -> y2
long long block1 = y1 / curr, block2 = y2 / curr;
if(block1 == block2) {
long long toadd = y2 - y1 + 1;
long long block11 = x1 / curr, block22 = x2 / curr;
if(block11 == block22) {
long long bazm = x2 - x1 + 1;
if(block11 % 2 == block1 % 2) {
first += bazm * toadd;
} else {
second += bazm * toadd;
}
}
else {
long long start = x1;
while(start / curr == block11) {
if(block11 % 2 == block1 % 2) {
first += toadd;
} else {
second += toadd;
}
start++;
}
start = x2;
while(start / curr == block22) {
if(block22 % 2 == block1 % 2) {
first += toadd;
} else {
second += toadd;
}
start--;
}
for(long long j = block11 + 1; j < block22; j++) {
if(j % 2 == block1 % 2) {
first += toadd * curr;
} else {
second += toadd * curr;
}
}
}
}
else {
long long block11 = x1 / curr, block22 = x2 / curr;
if(block11 == block22) {
long long toadd = x2 - x1 + 1;
long long start = y1;
while(start / curr == block1) {
if(block11 % 2 == block1 % 2) {
first += toadd;
} else {
second += toadd;
}
start++;
}
start = y2;
while(start / curr == block2) {
if(block11 % 2 == block2 % 2) {
first += toadd;
} else {
second += toadd;
}
start--;
}
for(long long j = block1 + 1; j < block2; j++) {
if(j % 2 == block11 % 2) {
first += toadd * curr;
} else {
second += toadd * curr;
}
}
}
else {
long long start = y1;
long long needFirst = 0, needSecond = 0;
while(start / curr == block1) {
if(block11 % 2 == block1 % 2) {
needFirst++;
} else {
needSecond++;
}
start++;
}
start = y2;
while(start / curr == block2) {
if(block11 % 2 == block2 % 2) {
needFirst++;
} else {
needSecond++;
}
start--;
}
long long bazm = (curr - x1 % curr + 1);
long long bazm2 = (x2 % curr + 1);
first += needFirst * bazm;
second += needSecond * bazm;
first += needFirst * bazm2;
second += needSecond * bazm2;
for(long long j = block1 + 1; j < block2; j++) {
if(j % 2 == block11 % 2) {
first += curr * bazm;
first += curr * bazm2;
needFirst += curr;
} else {
second += curr * bazm;
second += curr * bazm2;
needSecond += curr;
}
}
//
for(long long j = block11 + 1; j < block22; j++) {
if(block11 % 2 == j % 2) {
first += needFirst * curr;
second += needSecond * curr;
} else {
second += needFirst * curr;
first += needSecond * curr;
}
}
}
}
}
long long row = (n * n) / (curr * curr);
long long fs = row / 2, ss = row / 2;
if(row & 1) {
fs++;
}
fs = fs * (curr * curr);
ss = ss * (curr * curr);
ansi = min(ansi, fs - first + second);
ansi = min(ansi, ss - second + first);
}
void solve_() {
cin >> n >> k;
vector<long long> div = get_divisors(n);
for(int i = 1; i <= k; i++) {
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
points.push_back({{x1, y1}, {x2, y2}});
}
sort(all(points));
for(auto i: div) {
check(i);
}
printf("%lld\n", ansi);
}
int main() {
setIO();
auto solve = [&](int test_case)-> void {
while(test_case--) {
solve_();
}
};
int test_cases = 1;
solve(test_cases);
return 0;
}
