#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];
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 });
if (!(segs.back().first <= segs.back().second))
{
swap(segs.back().first, segs.back().second);
}
assert(segs.back().first <= segs.back().second);
}
sort(segs.begin(), segs.end(), [&](pair<int, int> a, pair<int, int> b) {return a.first + a.second < b.first + b.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> values;
for (int i = 0; i < (int)segs.size(); i++)
{
values.push_back(segs[i].first);
values.push_back(segs[i].second);
}
vector<int> what((int)values.size() + 1, 0);
multiset<int> low, high;
int sl = 0, sh = 0;
auto clr = [&]()
{
sl = 0;
sh = 0;
low.clear();
high.clear();
};
auto baga = [&](int x)
{
if (low.empty())
{
sh += x;
high.insert(x);
}
else
{
if (high.empty())
{
sl += x;
low.insert(x);
}
else
{
assert(!low.empty());
assert(!high.empty());
if (x >= *high.begin())
{
sh += x;
high.insert(x);
}
else
{
sl += x;
low.insert(x);
}
}
}
while ((int)high.size() - 1 >= (int)low.size() + 1)
{
assert(!high.empty());
sh -= *high.begin();
sl += *high.begin();
low.insert(*high.begin());
high.erase(high.begin());
}
while ((int)low.size() - 1 >= (int)high.size() + 1)
{
assert(!low.empty());
auto it = low.end();
it--;
sl -= *it;
sh += *it;
high.insert(*it);
low.erase(it);
}
assert(abs((int)low.size() - (int)high.size()) <= 1);
};
auto get = [&]()
{
assert(!low.empty());
assert(!high.empty());
assert((int)low.size() == (int)high.size());
int sol = 0, val = *high.begin();
sol += ((int)low.size()-(int)high.size()) * val;
sol -= sl;
sol += sh;
return sol;
};
clr();
int sol = INF;
for (int from = 0; from <= (int)values.size(); from += 2)
{
if (from >= 2)
{
baga(values[from - 2]);
baga(values[from - 1]);
what[from] += get();
}
}
clr();
for (int from = (int)values.size(); from >= 0; from -= 2)
{
if (from < (int)values.size())
{
baga(values[from]);
baga(values[from + 1]);
what[from] += get();
}
sol = min(sol, what[from]);
}
cout << sol + extra + n << "\n";
return 0;
}
