#include <bits/stdc++.h>
#define fr first
#define sc second
#define pii pair<int, int>
#define pb push_back
#define szof(s) (int)s.size()
#define all(s) s.begin(), s.end()
#define fastInp ios_base::sync_with_stdio(0); cin.tie(0);
#define int long long
using namespace std;
const int MAXN = (int)2e5 + 5;
const int INF = 1e18;
pair <char, int> st[MAXN];
pair <char, int> fn[MAXN];
bool ok(int pos) {
return (st[pos].first == fn[pos].first);
}
vector <int> vec;
int check(int pos) {
int sum = 0;
for (int el : vec) {
sum += abs(el - pos);
}
return sum;
}
signed main() {
fastInp;
int n, k;
cin >> k >> n;
assert(k == 1);
int side = 0;
int cnt = 0;
for (int i = 1; i <= n; i++) {
cin >> st[i].fr >> st[i].sc >> fn[i].fr >> fn[i].sc;
if (ok(i)) {
side += abs(st[i].sc - fn[i].sc);
} else {
cnt++;
vec.pb(st[i].sc);
vec.pb(fn[i].sc);
}
}
sort(all(vec));
int l = 0, r = 1e9;
while (r - l > 3) {
int m1 = l + (r - l) / 3;
int m2 = r - (r - l) / 3;
if (check(m1) < check(m2)) {
r = m2;
} else {
l = m1;
}
}
int bridge = INF;
for (int i = l; i <= r; i++) {
bridge = min(bridge, check(i) + cnt);
}
cout << side + bridge;
}
/*
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
