#include <bits/stdc++.h>
using namespace std;
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int N, K;
cin >> N >> K;
vector<vector<array<int, 3>>> rect(N + 1);
for (int i = 0; i < K; i++) {
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
x1--, y1--, y2--;
rect[x1].push_back({y1, y2, 1});
rect[x2].push_back({y1, y2, -1});
}
auto Even = [&](int L, int R, int d) {
int l = L % (2 * d) >= d ? L + d - L % d : L;
int r = R % (2 * d) >= d ? R - R % d - 1 : R;
return l > r ? pair {0, -1} : pair {l / (2 * d) * d + l % (2 * d), r / (2 * d) * d + r % (2 * d)};
};
auto Odd = [&](int L, int R, int d) {
int l = L % (2 * d) < d ? L + d - L % d : L;
int r = R % (2 * d) < d ? R - R % d - 1 : R;
return l > r ? pair {0, -1} : pair {l / (2 * d) * d + (l - d) % (2 * d), r / (2 * d) * d + (r - d) % (2 * d)};
};
long long answer = numeric_limits<long long>::max();
for (int d = 1; d < N; d++) {
if (N % d == 0) {
int N_even = N / (2 * d) * d + min(d, N % (2 * d)), N_odd = N / (2 * d) * d + max(0, N % (2 * d) - d);
int cnt_e = 0, cnt_o = 0;
long long answer_e = 0, answer_o = 0;
for (int i = 0; i < N; i++) {
for (auto [j1, j2, t] : rect[i]) {
auto [j1_e, j2_e] = Even(j1, j2, d);
auto [j1_o, j2_o] = Odd(j1, j2, d);
cnt_e += t * (j2_e - j1_e + 1);
cnt_o += t * (j2_o - j1_o + 1);
}
int r = (i / d) % 2;
answer_o += (r ? cnt_e : N_even - cnt_e) + (!r ? cnt_o : N_odd - cnt_o);
answer_e += (!r ? cnt_e : N_even - cnt_e) + (r ? cnt_o : N_odd - cnt_o);
}
answer = min({answer, answer_e, answer_o});
}
}
cout << answer << "\n";
}
