#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <bitset>
#include <fstream>
using namespace std;
#define int long long
#define ii pair <int, int>
#define app push_back
#define all(a) a.begin(), a.end()
#define bp __builtin_popcountll
#define ll long long
#define mp make_pair
#define x first
#define y second
#define Time (double)clock()/CLOCKS_PER_SEC
#define debug(x) std::cerr << #x << ": " << x << '\n';
#define FOR(i, n) for (int i = 0; i < n; ++i)
#define FORN(i, n) for (int i = 1; i <= n; ++i)
#define pb push_back
#define trav(a, x) for (auto& a : x)
using vi = vector<int>;
template <typename T>
std::istream& operator >>(std::istream& input, std::vector<T>& data)
{
for (T& x : data)
input >> x;
return input;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const pair <T, T> & data)
{
output << "(" << data.x << "," << data.y << ")";
return output;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const std::vector<T>& data)
{
for (const T& x : data)
output << x << " ";
return output;
}
ll div_up(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll div_down(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down
ll math_mod(ll a, ll b) { return a - b * div_down(a, b); }
#define tcT template<class T
#define tcTU tcT, class U
tcT> using V = vector<T>;
tcT> void re(V<T>& x) {
trav(a, x)
cin >> a;
}
tcT> bool ckmin(T& a, const T& b) {
return b < a ? a = b, 1 : 0;
} // set a = min(a,b)
tcT> bool ckmax(T& a, const T& b) {
return a < b ? a = b, 1 : 0;
}
ll gcd(ll a, ll b) {
while (b) {
tie(a, b) = mp(b, a % b);
}
return a;
}
signed main() {
#ifdef LOCAL
#else
#define endl '\n'
ios_base::sync_with_stdio(0); cin.tie(0);
#endif
int k, n;
cin >> k >> n;
int add = 0;
V <ii> a;
FOR (i, n) {
char t1, t2;
int l, r;
cin >> t1 >> l >> t2 >> r;
if (r < l) {
swap(l, r);
}
add += r - l;
if (t1 != t2) {
a.app(mp(l, r));
add++;
}
}
auto comp = [&] (ii a, ii b) {
return a.x + a.y < b.x + b.y;
};
sort(all(a), comp);
int ans = 1e18;
auto solve = [&] (V <ii> a) {
if (a.empty())
return 0ll;
vi c;
trav (e, a) {
c.app(e.x); c.app(e.y);
}
sort(all(c));
int ans = 0;
int sz = a.size();
int X = c[sz - 1];
trav (e, a) {
if (e.x > X) {
ans += e.x - X;
}
else if (e.y < X) {
ans += X - e.y;
}
}
return ans;
};
assert(k == 2);
int sz = a.size();
FOR (l, sz + 1) {
V <ii> L, R;
FOR (i, l) {
L.app(a[i]);
}
for (int i = l; i < sz; ++i) {
R.app(a[i]);
}
ckmin(ans, solve(L) + solve(R));
}
cout << 2 * ans + add << endl;
}
