#include<bits/stdc++.h>
#define fastio ios_base::sync_with_stdio(false);cin.tie(nullptr);
using namespace std;
struct line{
char x,z;
long long y,t;
}a[100009];
vector<long long>b[2];
vector<long long>pf[2];
int main()
{
fastio
int k,n;
cin>>k>>n;
long long ans=0;
for (int i=1;i<=n;i++){
cin>>a[i].x>>a[i].y>>a[i].z>>a[i].t;
if (a[i].x!=a[i].z){
b[a[i].x-'A'].push_back(a[i].y);
b[a[i].z-'A'].push_back(a[i].t);
}
else {
ans+=abs(a[i].y-a[i].t);
}
}
sort(b[0].begin(),b[0].end());
sort(b[1].begin(),b[1].end());
long long cal=1e16;
for (int i=0;i<2;i++){
pf[i].push_back(b[i][0]);
for (int j=1;j<(int)b[i].size();j++){
pf[i].push_back(b[i][j]+pf[i].back());
}
}
for (int i=1;i<=n;i++){
if (a[i].x!=a[i].z){
long long d=upper_bound(b[0].begin(),b[0].end(),a[i].y)-b[0].begin();
long long e=upper_bound(b[1].begin(),b[1].end(),a[i].y)-b[1].begin();
long long l1,r1,l2,r2;
if (d>0){
l1=d*a[i].y-pf[0][d-1];
r1=pf[0][(int)b[0].size()-1]-pf[0][d-1]-((int)b[0].size()-d)*a[i].y;
}
else {
l1=0;
r1=pf[0][(int)b[0].size()-1]-((int)b[0].size())*a[i].y;
}
if (e>0){
l2=e*a[i].y-pf[1][e-1];
r2=pf[1][(int)b[1].size()-1]-pf[1][e-1]-((int)b[1].size()-e)*a[i].y;
}
else {
l2=0;
r2=pf[1][(int)b[1].size()-1]-((int)b[1].size())*a[i].y;
}
//cout<<l1<<" "<<r1<<" "<<l2<<" "<<r2<<'\n';
cal=min(cal,l1+r1+l2+r2+ans+(long long)b[1].size());
d=upper_bound(b[0].begin(),b[0].end(),a[i].t)-b[0].begin();
e=upper_bound(b[1].begin(),b[1].end(),a[i].t)-b[1].begin();
if (d>0){
l1=d*a[i].t-pf[0][d-1];
r1=pf[0][(int)b[0].size()-1]-pf[0][d-1]-((int)b[0].size()-d)*a[i].t;
}
else {
l1=0;
r1=pf[0][(int)b[0].size()-1]-((int)b[0].size())*a[i].t;
}
if (e>0){
l2=e*a[i].t-pf[1][e-1];
r2=pf[1][(int)b[1].size()-1]-pf[1][e-1]-((int)b[1].size()-e)*a[i].t;
}
else {
l2=0;
r2=pf[1][(int)b[1].size()-1]-((int)b[1].size())*a[i].t;
}
//cout<<l1<<" "<<r1<<" "<<l2<<" "<<r2<<'\n';
cal=min(cal,l1+r1+l2+r2+(long long)b[1].size()+ans);
//cout<<e<<" "<<l2<<" "<<r2<<'\n';
}
}
cout<<cal;
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
}
