/*
PROG: source
LANG: C++11
_____
.' '.
/ 0 0 \
| ^ |
| \ / |
\ '---' /
'._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
struct chash
{
int operator()(int x) const
{
x ^= (x >> 20) ^ (x >> 12);
return x ^ (x >> 7) ^ (x >> 4);
}
int operator()(long long x) const
{
return x ^ (x >> 32);
}
};
template<typename T> using orderedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;
template<class T>
void readi(T &x)
{
T input = 0;
bool negative = false;
char c = ' ';
while (c < '-')
{
c = getchar();
}
if (c == '-')
{
negative = true;
c = getchar();
}
while (c >= '0')
{
input = input * 10 + (c - '0');
c = getchar();
}
if (negative)
{
input = -input;
}
x = input;
}
template<class T>
void printi(T output)
{
if (output == 0)
{
putchar('0');
return;
}
if (output < 0)
{
putchar('-');
output = -output;
}
int aout[20];
int ilen = 0;
while(output)
{
aout[ilen] = ((output % 10));
output /= 10;
ilen++;
}
for (int i = ilen - 1; i >= 0; i--)
{
putchar(aout[i] + '0');
}
return;
}
template<class T>
void ckmin(T &a, T b)
{
a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
a = max(a, b);
}
template<class T, class U>
T normalize(T x, U mod = 1000000007)
{
return (((x % mod) + mod) % mod);
}
long long randomizell(long long mod)
{
return ((1ll << 45) * rand() + (1ll << 30) * rand() + (1ll << 15) * rand() + rand()) % mod;
}
int randomize(int mod)
{
return ((1ll << 15) * rand() + rand()) % mod;
}
#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;
const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;
#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
int N, K;
ll ans = 0, best = LLINF;
vector<pll> ranges;
vector<ll> pos;
bool cmp(pll a, pll b)
{
return a.fi + a.se < b.fi + b.se;
}
ll f(ll a, ll b)
{
ll res = 0;
ll x = pos[a], y = pos[b];
int lo = 0, hi = N;
while(hi > lo)
{
int mid = (hi + lo) / 2;
if (ranges[mid].fi + ranges[mid].se >= x + y)
{
hi = mid;
}
else
{
lo = mid + 1;
}
}
for (int i = 0; i < lo; i++)
{
res += abs(x - ranges[i].fi) + abs(x - ranges[i].se);
}
for (int i = lo; i < N; i++)
{
res += abs(y - ranges[i].fi) + abs(y - ranges[i].se);
}
return res;
}
void solve(int L, int R, int optl, int optr)
{
if (L > R)
{
return;
}
ll cur = LLINF;
int mid = (L + R) / 2, opt = -1;
for (int i = max(mid + 1, optl); i <= optr; i++)
{
if (f(mid, i) <= cur)
{
opt = i;
cur = f(mid, i);
}
}
ckmin(best, cur);
solve(L, mid - 1, optl, opt);
solve(mid + 1, R, opt, optr);
}
int32_t main()
{
ios_base::sync_with_stdio(0);
srand(time(0));
// cout << fixed << setprecision(10);
// cerr << fixed << setprecision(10);
if (fopen("input.in", "r"))
{
freopen ("input.in", "r", stdin);
freopen ("output.out", "w", stdout);
}
// 1 5
// B 0 A 4
// B 1 B 3
// A 5 B 7
// B 2 A 6
// B 1 A 7
cin >> K >> N;
for (int i = 0; i < N; i++)
{
char c1; int x; char c2; int y;
cin >> c1 >> x >> c2 >> y;
if (c1 == 'B')
{
swap(c1, c2);
swap(x, y);
}
if (c1 == c2)
{
ans += abs(y - x);
}
else
{
ranges.PB({x, y});
// cerr << x << ' ' << y << endl;
}
}
N = ranges.size();
if (N == 0)
{
cout << ans << '\n';
return 0;
}
ans += N;
if (K == 1 || N == 1)
{
vector<ll> v;
for (pll x : ranges)
{
v.PB(x.fi);
v.PB(x.se);
}
// for (int x : v)
// {
// cerr << "lol " << x << endl;
// }
nth_element(v.begin(), v.begin() + (v.size() / 2) - 1, v.end());
ll pos = v[v.size() / 2 - 1];
for (ll x : v)
{
ans += abs(pos - x);
}
cout << ans << '\n';
return 0;
}
//now solve the problem
//min|a-x|+|b-x|, |a-y|+|b-y|
//it's clear you want to put at actual coordinates
//for less than x, obviously you wanna go to x
//x < a < b < y
//a-x+b-x < y-a + y-b => 2(a+b)<(2x+2y) => (a+b) < (x+y)
pos.reserve(2 * N);
for (int i = 0; i < N; i++)
{
pos.PB(ranges[i].fi);
pos.PB(ranges[i].se);
}
sort(pos.begin(), pos.end());
pos.erase(unique(pos.begin(), pos.end()), pos.end());
sort(ranges.begin(), ranges.end(), cmp);
// ll best = LLINF;
solve(0, pos.size() - 2, 1, pos.size() - 1);
ans += best;
cout << ans << '\n';
// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
return 0;
}
