#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
ll INF=1e18+10;
int main() {
//ios::sync_with_stdio(0);
//cin.tie(0);
//freopen("test_input.txt", "r", stdin);
//freopen("test_output.txt", "w", stdout);
int k,n;cin>>k>>n;
vector<pair<char,int>> a(n),b(n);
REP(i,0,n)cin>>a[i].F>>a[i].S>>b[i].F>>b[i].S;
//cout<<"a";
ll ans=0;
pii c;
REP(i,0,n){
if(a[i].F==b[i].F){
ans+=(ll)abs(a[i].S-b[i].S);
}
else {
if(a[i].S>b[i].S)swap(a[i].S,b[i].S);
c.PB({a[i].S,b[i].S});
}
}
int m=c.size();
if(m==0){
cout<<ans;
return 0;
}
sort(c.begin(),c.end());
if(k==2){
m--;
ans+=(ll)abs(c[m].F-c[m].S)+1;
c.pop_back();
}
vi ar;
REP(i,0,m)ar.PB(c[i].F);
REP(i,0,m)ar.PB(c[i].S);
sort(ar.begin(),ar.end());
REP(i,0,m*2)ans+=(ll)abs(ar[i]-ar[m]);
cout<<ans+(ll)m;
}
