#include <bits/stdc++.h>
using namespace std;
#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)
using vi = vector<int>;
using ii = pair<int, int>;
using vii = vector<ii>;
using ll = long long;
using ld = long double;
using vll = vector<ll>;
using vb = vector<bool>;
using pll = pair<ll, ll>;
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define sum(x) accumulate(all(x), 0LL)
#define pb push_back
#define eb emplace_back
#define fst first
#define snd second
struct ds {
struct : multiset<int> {
ll sum = 0;
void ins(int x) {
sum += x;
insert(x);
}
void del(int x) {
sum -= x;
erase(find(x));
}
} left, right;
void balance() {
while (sz(left) > sz(right)) {
int x = *left.rbegin();
left.del(x);
right.ins(x);
}
while (sz(right) > sz(left) + 1) {
int x = *right.begin();
right.del(x);
left.ins(x);
}
}
void insert(int x) {
if (!right.empty() && x < *right.begin()) left.ins(x);
else right.ins(x);
balance();
}
void erase(int x) {
if (left.count(x)) left.del(x);
else right.del(x);
balance();
}
ll query() {
return - left.sum + right.sum + *right.begin() * (sz(left) - sz(right));
}
};
const ll INF = 1e18;
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int k, n;
cin >> k >> n;
vii v;
ll base = 0;
forn(i, n) {
char type[2]; int pos[2];
forn(j, 2) cin >> type[j] >> pos[j];
if (type[0] == type[1]) base += abs(pos[0] - pos[1]);
else v.eb(pos[0], pos[1]), base++;
}
n = sz(v);
sort(all(v), [&](ii a, ii b) {
return a.fst + a.snd < b.fst + b.snd;
});
ds pref, suff;
forn(i, n) suff.insert(v[i].fst), suff.insert(v[i].snd);
ll ret = suff.query();
if (k == 1) {
ret += base;
cout << ret << '\n';
return 0;
}
forn(i, n - 1) {
pref.insert(v[i].fst), pref.insert(v[i].snd);
suff.erase(v[i].fst), suff.erase(v[i].snd);
ret = min(ret, pref.query() + suff.query());
}
ret += base;
cout << ret << '\n';
return 0;
}
