#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#pragma GCC target("avx,avx2,fma")
//#pragma GCC optimize("Ofast,unroll-loops")
using namespace std;
using namespace __gnu_pbds;
#define pb push_back
#define all(x) x.begin(),x.end()
#define int long long
// #define double long double
#define ar array
#define mrand(a, b) uniform_int_distribution<int>(a, b)(rng)
template<class T>bool umax(T &a,T b){if(a<=b){a=b;return true;}return false;}
template<class T>bool umin(T &a,T b){if(b<a){a=b;return true;}return false;}
template<class T> using ste = tree<T, null_type, less_equal<T>,
rb_tree_tag, tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int binpow(int a, int b, int m){
if(b <= 0)return 1;
if(b % 2 == 0){
int c = binpow(a,b/2,m);
return (c*c)%m;
}
return (binpow(a,b-1,m)*a)%m;
}
int divi(int a, int b, int m){
return (a*(binpow(b,m-2, m)))%m;
}
namespace FAST {
template<typename T>
istream &operator>>(istream &cin, vector<T> &a) {
for (T &i: a) cin >> i;
return cin;
}
template<typename T>
ostream &operator<<(ostream &cout, vector<T> &a) {
for (T i: a) cout << i << ' ';
return cout;
}
}
using namespace FAST;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;
const int N = 1e2 + 5;
const int md = 998244353;
int rev(int a, int m){
if (a == 1)return 1;
return (1 - rev(m % a, a) * m) / a + m;
}
struct Bit {
vector<int> b, b2;
int n;
Bit(int n) {
this->n = n + 1;
b.assign(n + 1, 0);
b2.assign(n+1, 0);
}
void add(vector<int>&b, int idx, int x){
while(idx <= n){
b[idx] += x;
idx += idx & -idx;
}
}
void upd(int l, int r, int x){
add(b, l, x);
add(b, r+1, -x);
add(b2, l, x*(l-1));
add(b2, r+1, -x*r);
}
int sum(vector<int>&b, int idx){
int res = 0;
while(idx > 0){
res += b[idx];
idx -= idx & -idx;
}
return res;
}
int pref(int idx){
return sum(b, idx) * idx - sum(b2, idx);
}
int get(int l, int r){
return pref(r) - pref(l-1);
}
};
int n,m,k;
int ans;
struct Tree{
int sz;
vector<vector<int>>t, pref;
Tree(int n){
this->sz = n;
t.resize(sz * 4 + 5);
pref.resize(sz * 4 + 5);
}
void merge(vector<int> &a, vector<int> &b, vector<int> &c, vector<int>&d){
int i = 0, j = 0;
while(i < a.size() && j < b.size()){
if(a[i] <= b[j])c.pb(a[i++]);
else c.pb(b[j++]);
}
while(i < a.size())c.pb(a[i++]);
while(j < b.size())c.pb(b[j++]);
d.pb(c[0]);
for(int i = 1;i<c.size();i++){
d.pb(d[i-1] + c[i]);
}
}
void build(int tl, int tr, int v, vector<ar<int,2>> &op){
if(tl == tr){
t[v].pb(op[tl][1]);
pref[v].pb(op[tl][1]);
return;
}
int tm = (tl + tr) / 2;
build(tl, tm, v*2, op);
build(tm+1, tr, v*2+1, op);
merge(t[v*2], t[v*2+1], t[v], pref[v]);
}
void get(int tl, int tr, int v, int l, int r, int val){
if(r < tl || tr < l || r < l)return;
if(l <= tl && tr <= r){
int x = 0, y = t[v].size() - 1, ans2 = -1;
while(x <= y){
int mid = (x + y) / 2;
if(t[v][mid] < val){
ans2 = mid;
x = mid + 1;
}
else y = mid - 1;
}
if(ans2 == -1)return;
ans += val * (ans2 + 1) - pref[v][ans2];
return;
}
int tm = (tl + tr) / 2;
get(tl, tm, v*2, l, r, val);
get(tm+1, tr, v*2+1, l, r, val);
}
};
void solve(){
cin >> k >> n;
vector<ar<int,2>>vs;
set<int>v_;
vector<int>v;
int sum = 0;
for(int i = 1;i<=n;i++){
char a,b;
int l,r;
cin >> a >> l >> b >> r;
if(l > r)swap(l, r);
if(a != b){
vs.pb({l, r});
v_.insert(l);
v_.insert(r);
sum += r-l + 1;
}
else sum += r-l;
}
for(auto to : v_){
v.pb(to);
}
sort(all(vs));
sort(all(v));
int sz = vs.size();
if(sz == 0){
cout << sum << "\n";
return;
}
vector<int>pref(sz + 5);
pref[0] = vs[0][0];
for(int i = 1;i<sz;i++){
pref[i] = pref[i-1] + vs[i][0];
}
Tree t(sz + 5);
t.build(0, sz, 1, vs);
int l = 0, r = 1e9, ans3 = -1;
while(l <= r){
int l1 = l + (r-l)/3;
int r1 = r - (r-l)/3;
int sum1 = 0, sum2 = 0;
int pos1 = -1, pos2 = -1;
int x = 0, y = sz - 1;
while(x <= y){
int mid = (x + y) / 2;
if(vs[mid][0] < l1){
x = mid + 1;
pos1 = mid;
}
else y = mid - 1;
}
x = 0, y = sz - 1;
while(x <= y){
int mid = (x + y) / 2;
if(vs[mid][0] < l1){
x = mid + 1;
pos2 = mid;
}
else y = mid - 1;
}
ans = 0;
if(pos1 != -1)
t.get(0, sz, 1, 0, pos1, l1);
sum1 += pref[sz - 1] - ((pos1 == -1) ? 0 : pref[pos1]) - ((pos1 == -1) ? sz-1 : (sz-1 - pos1)) * l1;
sum1 += ans;
ans = 0;
if(pos2 != -1)
t.get(0, sz, 1, 0, pos2, r1);
sum2 += pref[sz - 1] - ((pos2 == -1) ? 0 : pref[pos2]) - ((pos2 == -1) ? sz-1 : (sz-1 - pos2)) * r1;
sum2 += ans;
if(sum1 <= sum2){
ans3 = sum1 * 2;
r = r1 - 1;
}
else{
ans3 = sum2 * 2;
l = l1 + 1;
}
//~ cout << sum1 << "\n";
//~ return;
}
cout << ans3 + sum << "\n";
}
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
//
5 6 1
1 1
-1 10
-1 10
-1 1000000000
-1 10
1 2 1
2 3 1
3 1 1
3 4 1
4 5 1
5 3 1
*/
signed main()
{
//~ freopen("road.in", "r", stdin);
//~ freopen("road.out", "w", stdout);
ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
int tt=1;//cin >> tt;
while(tt--)solve();
}
