#include <iostream>
#include <iomanip>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cassert>
#include <string>
#include <set>
#include <map>
#include <random>
#include <bitset>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <deque>
#include <queue>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
using namespace std;
using ll = long long;
using ul = unsigned long long;
using ld = long double;
const int N = 200001;
ll s1[N], s2[N], d1[N], d2[N];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int k, n, l, r;
ll ans = 0;
cin >> k >> n;
char c1, c2;
vector<int> li;
vector<pair<int, int>> a;
rep(i, n) {
cin >> c1 >> l >> c2 >> r;
if (l > r)
swap(l, r);
ans += r - l;
if (c1 == c2)
continue;
ans++;
li.push_back(l);
li.push_back(r);
a.push_back({l, r});
}
n = a.size();
sort(all(li));
li.resize(unique(all(li)) - li.begin());
sort(all(a), [](auto &p1, auto &p2) {return p1.first + p1.second < p2.first + p2.second;});
ll ca = 0, pos = 0, ck = 0;
rep(i, n) {
a[i].first = lower_bound(all(li), a[i].first) - li.begin();
a[i].second = lower_bound(all(li), a[i].second) - li.begin();
if (pos < a[i].first) {
ca += li[a[i].first] - li[pos];
ck--;
}
else if (a[i].second <= pos) {
ca += li[pos] - li[a[i].second];
ck++;
}
d1[a[i].first]++;
d1[a[i].second]++;
while (ck < 0) {
ca += ck * (li[pos + 1] - li[pos]);
pos++;
ck += d1[pos];
}
s1[i + 1] = ca;
}
ll mn = s1[n];
pos = li.size() - 1;
ck = ca = 0;
for (int i = n - 1; i >= 0; i--) {
if (pos <= a[i].first) {
ca += li[a[i].first] - li[pos];
ck++;
}
else if (a[i].second < pos) {
ca += li[pos] - li[a[i].second];
ck--;
}
d2[a[i].first]++;
d2[a[i].second]++;
while (ck < 0) {
ca += ck * (li[pos] - li[pos - 1]);
pos--;
ck += d2[pos];
}
if (k > 1)
mn = min(mn, s1[i] + ca);
}
cout << ans + mn * 2;
}
