#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define FOR(a , b) for(int i = a;i <= b;i++)
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MXN = 100005;
const int INF = 1e18;
const int mod = 1e9 + 7;
int k , n , s[MXN] , t[MXN];
char p[MXN] , q[MXN];
int calc(int pa , int pb)
{
int res = 0;
for(int i = 1;i <= n;i++)
{
if(p[i] == q[i])
{
res += (abs(s[i] - t[i]));
continue;
}
++res;
res += min((abs(s[i] - pa)) + (abs(t[i] - pa)) , (abs(s[i] - pb)) + (abs(t[i] - pb)));
}
return res;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> k >> n;
vector < int > pos; map < int , int > used;
for(int i = 1;i <= n;i++)
{
cin >> p[i] >> s[i] >> q[i] >> t[i];
if(!used[s[i]]){
pos.push_back(s[i]);
used[s[i]] = 1;
}
if(!used[t[i]]){
pos.push_back(t[i]);
used[t[i]] = 1;
}
}
int res = INF;
for(int i = 0;i < pos.size();i++)
{
int l = 1 , r = i , mn = i;
while(l <= r){
int mid = (l + r) >> 1;
if(calc(pos[i] , pos[mid]) < calc(pos[i] , pos[mid - 1])){
mn = min(mn , mid); r = mid - 1;
}
else l = mid + 1;
}
res = min(res , calc(pos[i] , pos[mn]));
l = i , r = pos.size() - 2;
int mx = 0;
while(l <= r){
int mid = (l + r) >> 1;
if(calc(pos[i] , pos[mid]) < calc(pos[i] , pos[mid + 1])){
mx = max(mx , mid); l = mid + 1;
}
else r = mid - 1;
}
res = min(res , calc(pos[i] , pos[mx]));
}
cout << res << endl;
}
