#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = (int) 1e9 + 123;
const ll LINF = (ll) 1e18 + 123;
#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int) (x).size())
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
bool mini(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
bool maxi(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
void run();
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
return 0;
}
const int N = (int) 1e5 + 123;
int k, n;
vector<pair<ll, ll>> a;
vector<ll> cool;
ll total;
void solve1() {
vector<ll> p;
{
for (auto &it : a) {
p.pb(it.first);
p.pb(it.second);
}
sort(all(p));
}
int k = sz(p) / 2;
ll x = p[k];
ll ans = 0;
for (ll y : p) ans += abs(x - y);
ans += total;
cout << ans << "\n";
}
ll f(ll x1, ll x2) {
ll cur = 0;
for (auto &it : a) {
ll best = LINF;
mini(best, abs(it.first - x1) + abs(it.second - x1));
mini(best, abs(it.first - x2) + abs(it.second - x2));
cur += best;
}
return cur;
};
ll solve(int l, int r, int tl, int tr) {
if (l >= r) {
return LINF;
}
int mid = (l + r) / 2;
ll ans = LINF;
int opt = tl;
rep(i, tl, min(mid + 1, tr)) {
if (mini(ans, f(cool[i], cool[mid]))) {
opt = i;
}
}
mini(ans, solve(l, mid, tl, opt + 1));
mini(ans, solve(mid + 1, r, opt, tr));
return ans;
}
void run() {
cin >> k >> n;
rep(i, 0, n) {
char t1, t2;
ll x1, x2;
cin >> t1 >> x1 >> t2 >> x2;
if (t1 == t2) {
total += abs(x1 - x2);
} else {
if (x1 > x2) {
swap(t1, t2);
swap(x1, x2);
}
a.pb({x1, x2});
cool.pb(x1);
cool.pb(x2);
}
}
sort(all(cool));
cool.resize(unique(all(cool)) - cool.begin());
sort(all(a));
n = sz(a);
total += n;
if (k == 1) {
solve1();
return;
}
if (n == 0) {
cout << total << "\n";
return;
}
ll ans = solve(0, sz(cool), 0, sz(cool));
ans += total;
cout << ans << "\n";
}
