#include <cmath>
#include <functional>
#include <fstream>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <map>
#include <list>
#include <time.h>
#include <math.h>
#include <random>
#include <deque>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <cassert>
#include <bitset>
#include <sstream>
#include <chrono>
#include <cstring>
#include <numeric>
using namespace std;
#define int long long
const int INF = (int)1e18 + 7;
pair<int, int> _rd_()
{
string s;
int i;
cin >> s >> i;
assert(s == "A" || s == "B");
return { s == "B", i };
}
const int N = (int)1e5 + 7;
int k;
int n;
int extra;
pair<int, int> c1[N], c2[N];
struct T
{
int fi;
int sc;
};
signed main()
{
#ifdef ONPC
FILE* stream;
freopen_s(&stream, "input.txt", "r", stdin);
#else
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#endif
cin >> k >> n;
{
int y = 0;
for (int i = 1; i <= n; i++)
{
c1[i] = _rd_();
c2[i] = _rd_();
if (c1[i].first == c2[i].first)
{
extra += abs(c1[i].second - c2[i].second);
continue;
}
y++;
c1[y] = c1[i];
c2[y] = c2[i];
}
n = y;
}
if (n == 0)
{
cout << extra << "\n";
return 0;
}
if (k == 1)
{
vector<int> coords;
for (int i = 1; i <= n; i++)
{
coords.push_back(c1[i].second);
coords.push_back(c2[i].second);
}
nth_element(coords.begin(), coords.begin() + n - 1, coords.end());
int su = 0;
for (int i = 0; i < 2 * n; i++)
{
su += abs(coords[i] - coords[n - 1]);
}
cout << su + extra + n << "\n";
return 0;
}
assert(k == 2);
set<int> s;
for (int i = 1; i <= n; i++)
{
s.insert(c1[i].second);
s.insert(c2[i].second);
if (c1[i].second > c2[i].second)
{
swap(c1[i], c2[i]);
}
}
vector<pair<int, int>> segs;
for (int i = 1; i <= n; i++)
{
segs.push_back({ c1[i].second, c2[i].second });
}
vector<int> co;
for (auto& x : s)
{
co.push_back(x);
}
assert(!co.empty());
co.push_back(co.back());
assert((int)co.size() >= 2);
vector<int> coords;
for (int i = 1; i <= n; i++)
{
coords.push_back(c1[i].second);
coords.push_back(c2[i].second);
}
sort(coords.begin(), coords.end());
vector<int> lft((int)co.size(), 0);
vector<int> rgh((int)co.size(), 0);
for (int i = 0; i < (int)co.size(); i++)
{
for (auto& s : segs)
{
if (s.second < co[i])
{
lft[i] += co[i] - s.second;
}
}
for (auto& s : segs)
{
if (co[i] < s.first)
{
rgh[i] += s.first - co[i];
}
}
}
int sol = INF;
for (int px = 0; px < (int)co.size(); px++)
{
vector<T> ovr;
for (auto& s : segs)
{
if (co[px] <= s.first)
{
ovr.push_back({ s.first, s.second });
}
}
sort(ovr.begin(), ovr.end(), [&](T a, T b) {return a.sc < b.sc; });
for (int py = px + 1; py < (int)co.size(); py++)
{
int x = co[px];
int y = co[py];
int cur = 0;
for (int i = 0; i < (int)ovr.size(); i++)
{
if (x + y <= ovr[i].fi + ovr[i].sc)
{
cur += max(0LL, y - ovr[i].sc);
}
else
{
cur += ovr[i].fi - x;
}
}
sol = min(sol, cur + lft[px] + rgh[py]);
}
}
for (int i = 1; i <= n; i++)
{
extra += abs(c1[i].second - c2[i].second);
}
cout << 2 * sol + extra + n << "\n";
return 0;
}
