// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=1e9+7;
const int inf = 1e9;
const int LOG=17;
const int N=1e5+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
void solve()
{
cin >> k >> n;
vector<pair<int,int>>a,b;
int f=0;
for (int i=0;i<n;i++){
char s,t;
cin >> s >> x >> t >> y;
if (s==t){
f+=abs(x-y);
}
else{
a.push_back({x,y});
b.push_back({y,x});
}
}
sort(a.begin(),a.end());
sort(b.begin(),b.end());
n=a.size();
if (!n){
cout << f << endl;
return;
}
int u=a[0].fi;
int j=0;
c=0;
int d=0;
for (int i=0;i<n;i++){
d++;
while (b[j].fi<a[i].fi){
d--;
j++;
}
if (d>c){
c=d;
u=b[j].fi;
}
}
c=0;
for (auto i:a){
c+=abs(i.fi-u)+abs(i.se-u)+1;
}
cout << c+f << endl;
}
signed main()
{
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
