#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
/*
Competitive Programming notes that I need to study & fix my dumbass self:
1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you
2. Stress:
- Always try generating big testcases and try if they run
3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time
Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'
+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'
I hate offline because I am dumb
*/
typedef pair<int, int> ii;
const int N = 3e5+5;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n,k;
int cw[N], cb[N];
vector<int> divisor;
int block(int i, int d)
{
return (i-1) / d;
}
int st(int i, int d)
{
return i*d + 1;
}
int ed(int i, int d)
{
return i*d + d;
}
int odd(int l, int r, int d)
{
int bl = block(l, d), br = block(r, d);
if (bl == br)
{
if (bl % 2 == 1) return r-l+1;
else return 0;
} else if (br == bl+1)
{
if (bl % 2 == 1) return ed(bl, d) - l + 1;
else return r - st(br, d) + 1;
} else
{
int ret = 0;
if (bl % 2 == 1) ret += ed(bl, d) - l + 1;
if (br % 2 == 1) ret += r - st(br, d) + 1;
int lo = bl+1, hi = br-1;
lo += 1 - (lo % 2); hi -= 1 - (hi % 2);
if (lo <= hi) ret += ((hi-lo) / 2 + 1) * d;
return ret;
}
}
int even(int l, int r, int d)
{
int bl = block(l, d), br = block(r, d);
if (bl == br)
{
if (bl % 2 == 0) return r-l+1;
else return 0;
} else if (br == bl+1)
{
if (bl % 2 == 0) return ed(bl, d) - l + 1;
else return r - st(br, d) + 1;
} else
{
int ret = 0;
if (bl % 2 == 0) ret += ed(bl, d) - l + 1;
if (br % 2 == 0) ret += r - st(br, d) + 1;
int lo = bl+1, hi = br-1;
lo += (lo % 2); hi -= (hi % 2);
if (lo <= hi) ret += ((hi-lo) / 2 + 1) * d;
return ret;
}
}
void solve()
{
cin>>n>>k;
for (int i = 1; i < n; i++) if (n % i == 0) divisor.pb(i);
int sum = 0;
while (k--)
{
int x1, x2, y1, y2;
cin>>x1>>y1>>x2>>y2;
int h = (x2-x1+1), w = (y2-y1+1);
int a = h*w;
sum += a;
for (auto i : divisor)
{
int x = odd(x1, x2, i), y = even(y1, y2, i);
int bl = x*y + (h-x) * (w-y);
cb[i] += bl;
cw[i] += a - bl;
}
}
// for (auto i : divisor)
// {
// cout<<i<<" "<<cb[i]<<" "<<cw[i]<<endl;
// }
int ans = inf;
for (auto i : divisor)
{
int j = n/i;
int b = (j*j + 1) / 2, w = j*j - b;
ans = min({ans, sum - cw[i] + b*i*i - cw[i], sum - cb[i] + w*i*i - cb[i]});
}
cout<<ans;
}
/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
// cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
