/* made by amunduzbaev */
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define ff first
#define vv vector
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define sz(x) (int)x.size()
#define tut(x) array<int, x>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define NeedForSpeed ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define int long long
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vii;
typedef vector<pii> vpii;
template<class T> bool umin(T& a, const T& b) { return a > b? a = b, true:false; }
template<class T> bool umax(T& a, const T& b) { return a < b? a = b, true:false; }
//void usaco(string s) { freopen((s+".in").c_str(),"r",stdin);
//freopen((s+".out").c_str(),"w",stdout); }
//template<class T> tree<T,
//less<T>, null_type, rb_tree_tag,
//tree_order_statistics_node_update> ordered_set;
const int N = 1e5+5;
const int mod = 1e9+7;
const ll inf = 1e16;
const ld Pi = acos(-1);
#define MULTI 0
int n, m, k, ans, q, res, a[N];
int l[N], r[N];
int pref[N], suf[N];
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
void solve(int t_case){
cin>>k>>n;
for(int i=0, last = 0;i<n;i++){
char s1, s2; int p1, p2;
cin>>s1>>p1>>s2>>p2;
if(s1 == s2) res += abs(p1 - p2);
else l[last] = min(p1, p2), r[last] = max(p1, p2), last++, m = last;
} if(k == 1){
vpii tt;
for(int i=0;i<m;i++){
tt.pb({l[i], 0});
tt.pb({r[i], 1});
} sort(all(tt));
n = sz(tt);
int cost = 0, cnt = 0, cntl = 0;
for(int i=0;i<n;){
int j = i;
if(i) cost += abs(tt[i-1].ff - tt[i].ff) * cnt * 2 + abs(tt[i-1].ff - tt[i].ff) * cntl;
while(j < n && tt[i].ff == tt[j].ff) pref[j] = cost, j++;
while(i < j) {
if(tt[i].ss) cntl--, cnt++;
else cntl++;
i++;
}
}
reverse(all(tt));
cnt = cntl = cost = 0;
for(int i=0;i<n;){
int j = i;
if(i) cost += abs(tt[i-1].ff - tt[i].ff) * cnt * 2 + abs(tt[i-1].ff - tt[i].ff) * cntl;
while(j < n && tt[i].ff == tt[j].ff) suf[n - j - 1] = cost, j++;
while(i < j) {
if(!tt[i].ss) cntl--, cnt++;
else cntl++;
i++;
}
} ans = mod;
for(int i=0;i<n;i++) umin(ans, pref[i] + suf[i]);
cout<<res + ans + m<<"\n";
} else {
}
}
signed main(){
NeedForSpeed
if(!MULTI) {
solve(1);
} else {
int t; cin>>t;
for(int t_case = 1; t_case <= t; t_case++) solve(t_case);
} return 0;
}
