//Challenge: Accepted
#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <cmath>
#include <utility>
#include <assert.h>
using namespace std;
void debug() {cout << endl;}
template <class T, class ...U> void debug(T a, U ... b) { cout << a << " "; debug(b...);}
template <class T> void pary(T l, T r) {
while (l != r) {cout << *l << " ";l++;}
cout << endl;
}
#define ll long long
#define ld long double
#define maxn 100005
#define pii pair<int, int>
#define pdd pair<double, double>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
pii a[maxn], b[maxn];
ll pref[maxn], suf[maxn];
void solve(int n, pii arr[], ll ans[]) {
ll lc = 0, rc = 0, cur = 0, cost = 0;
priority_queue<pii, vector<pii>, greater<pii> > pq;
for (int i = 0;i < n;i++) {
if (arr[i].ff > cur) pq.push({arr[i].ff, 0}), rc++, cost += arr[i].ff - cur;
pq.push({arr[i].ss, 1});
while (pq.size()) {
pii seg = pq.top();pq.pop();
ll dis = seg.ff - cur;
if (dis == 0 || (lc - rc) * dis < 0) {
cost += (lc - rc) * dis;
cur = seg.ff;
if (seg.ss == 0) rc--;
else lc++;
} else {
pq.push(seg);
break;
}
}
ans[i] = cost;
}
}
int main() {
int k, n;
cin >> k >> n;
int cross = 0;
ll sum = 0;
int m = 0, ma = 0;
for (int i = 0;i < n;i++) {
char p, q;
int s, t;
cin >> p >> s >> q >> t;
if (s > t) swap(s, t);
sum += t - s;
ma = max(ma, t);
if (p != q) {
a[m++] = {s, t};
}
}
sort(a, a + m, [&](pii x, pii y) {return x.ff + x.ss < y.ff + y.ss;});
solve(m, a, pref);
ll ans = pref[m - 1];
if (k == 2) {
for (int i = 0;i < m;i++) {
b[i] = a[m - 1 - i];
b[i] = {ma - b[i].ss, ma - b[i].ff};
}
solve(m, b, suf);
ans = min(pref[m - 1], suf[m - 1]);
for (int i = 0;i < m - 1;i++) {
ans = min(ans, pref[i] + suf[m - 2 - i]);
}
}
cout << 2 * ans + sum + m << endl;
}
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
