#include <bits/stdc++.h>
using namespace std;
inline void read() {}
template <class S>
inline void read(S &arg) {
cin >> arg;
}
template <class S>
inline void readA(S Lptr, S Rptr) {
while (Lptr != Rptr) {
read(*Lptr);
Lptr++;
}
}
template <class S, class... T>
inline void read(S &arg, T &... rest) {
read(arg);
read(rest...);
}
inline void write() {}
template <class S>
inline void write(S arg) {
cout << arg;
}
template <class S>
inline void weiteA(S Lptr, S Rptr) {
if (Lptr != Rptr) {
write(*Lptr);
Lptr++;
}
while (Lptr != Rptr) {
write(' ');
write(*Lptr);
Lptr++;
}
}
template <class S, class... T>
inline void write(S arg, T... rest) {
write(arg);
write(' ');
write(rest...);
}
#define rep(i, j, k) for (int i = j; i < (int)k; i++)
#define pb push_back
#define mt make_tuple
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
template <class T, class S>
inline bool smin(T &a, S b) {
return (T)b < a ? a = b, 1 : 0;
}
template <class T, class S>
inline bool smax(T &a, S b) {
return a < (T)b ? a = b, 1 : 0;
}
constexpr int MOD = 998244353;
constexpr int N = 1e6 + 10;
template <typename T>
inline T mod(T &v) {
return v = (v % MOD + MOD) % MOD;
}
template <typename S, typename T>
inline S add(S &l, T r) {
return mod(l += r);
}
ll po(ll v, ll u) {
return u ? po(v * v % MOD, u >> 1) * (u & 1 ? v : 1) % MOD : 1;
}
int k, n, cnt;
ll bias, local;
pii p[N];
multiset<int> st[2];
multiset<int>::iterator it;
ll res[N][2];
inline void insert(int b, pii a) {
st[b].insert(a.first);
st[b].insert(a.second);
}
inline void f(int id) {
insert(id, p[0]);
res[0][id] = p[0].second - p[0].first;
it = st[id].begin();
rep(i, 1, cnt) {
insert(id, p[i]);
int del = abs(p[i].first - *it) + abs(p[i].second - *it);
if (p[i].first >= *it) {
int tmp = *it;
it++;
del -= 2 * (*it - tmp);
} else if (*it > p[i].second)
it--;
res[i][id] = res[i - 1][id] + del;
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
read(k, n);
rep(i, 0, n) {
char a, b;
int A, B;
read(a, A, b, B);
if (A > B) swap(A, B);
p[cnt++] = {A, B};
if (a == b) {
bias += abs(A - B);
cnt--;
}
}
bias += cnt;
sort(p, p + cnt,
[](pii l, pii r) { return l.first + l.second < r.first + r.second; });
f(0);
reverse(p, p + cnt);
f(1);
if (k == 1) return write(bias + res[cnt - 1][0]), 0;
ll best = bias + res[cnt - 1][0];
rep(i, 1, cnt) smin(best, bias + res[i - 1][0] + res[cnt - i - 1][1]);
write(best);
return 0;
}
