#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2e5 + 5;
const int INF = 1e18;
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int k, n, tot = 0;
cin >> k >> n;
set < int > L, R;
vector < array < int , 2 > > v;
for(int i = 0; i < n; i++){
char ty1, ty2;
int cor1, cor2;
cin >> ty1 >> cor1 >> ty2 >> cor2;
if(cor1 > cor2)
swap(cor1, cor2);
L.insert(cor1);
R.insert(cor2);
if(ty1 == ty2){
tot += abs(cor1 - cor2);
}
else {
v.push_back({cor1, cor2});
}
}
int mn = INF;
for(auto d1 : L){
for(auto d2 : R){
int cur = tot;
int x = min(d1, d2);
int y = max(d1, d2);
for(auto [l, r] : v){
int select = min(abs(x - l) + abs(x - r), abs(y - l) + abs(y - r)) + 1;
cur += select;
}
mn = min(mn, cur);
}
}
cout << mn << endl;
}
