#include <bits/stdc++.h>
using namespace std;
long long const INF=1e18;
int const MAX=2e5+5;
struct location{
int pos;
char type;
int id;
bool operator<(location ot){
return pos<ot.pos;
}
}loc[MAX];
int k,n;
long long s_init;
int total_loc;
void read(){
cin>>k>>n;
int i;
for(i=1;i<=n;++i){
char t1,t2;
int p1,p2;
cin>>t1>>p1>>t2>>p2;
s_init+=abs(p2-p1);
if(t1!=t2){
loc[++total_loc]={p1,t1,i};
loc[++total_loc]={p2,t2,i};
++s_init;
}
}
sort(loc+1,loc+total_loc+1);
}
bool gasit_per[MAX];
void minself(long long&x,long long val){
if(x>val)
x=val;
}
long long spate[MAX],fata[MAX];
void precalc(int inc,int fin,long long v[],int incr){
long long nr=0;
int nrper=0;
int i;
for(i=1;i<=n;++i)
gasit_per[i]=0;
for(i=inc;i!=fin+incr;i+=incr){
if(i!=inc)
nr+=2LL*nrper*abs(loc[i-incr].pos-loc[i].pos);
v[i]=nr;
if(!gasit_per[loc[i].id])
gasit_per[loc[i].id]=1;
else
++nrper;
}
}
long long solve(){
precalc(1,total_loc,spate,1);
precalc(total_loc,1,fata,-1);
long long rasp=INF;
int i;
for(i=1;i<=total_loc;++i)
minself(rasp,spate[i]+fata[i]);
return rasp;
}
int main()
{
read();
if(total_loc)
cout<<solve()+s_init;
else
cout<<s_init;
return 0;
}
