//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];
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++) {
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 ((lc - rc) * dis <= 0) {
cost += (lc - rc) * dis;
cur = seg.ff;
if (seg.ss == 0) rc--;
else lc++;
} else {
pq.push(seg);
break;
}
}
ans[n - 1] = cost;
/*
for (int i = 0;i < n;i++) {
//debug(arr[i].ff, arr[i].ss);
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 ((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;
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;
if (p != q) {
a[m++] = {s, t};
}
}
sort(a, a + m, [&](pii x, pii y) {return x.ff + x.ss < y.ff + y.ss;});
//sort(a, a + m);
solve(m, a, pref);
//pary(pref, pref + m);
cout << 2 * pref[m - 1] + 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
*/
