#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define fst first
#define snd second
#define pb push_back
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(),x.end()
#define forn(i,a,b) for(int i = a; i< b; i++)
#define mset(a,v) memset(a,v,sizeof(a))
#define FIN ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
template<typename T>
using iset = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
vector<pair<ll,ll>> rng;
set<ll> vals;
ll pA = -1;
ll resauxA = 0;
iset<pair<ll,ll>> leftA;
iset<pair<ll,ll>> rightA;
//acomodar A
// a partir de la posicion del puente lo acomoda segun sea necesario (izq o der)
void acomodarA(){
while(true){
ll cleft=0;
auto lait = leftA.lower_bound({pA+1,-1});
if(lait!=leftA.end()){
cleft=SZ(leftA)-leftA.order_of_key(*lait);
}
ll cright=SZ(rightA);
auto rait = rightA.upper_bound({pA,1000000000000000});
if(rait!=rightA.end()){
cright=rightA.order_of_key(*rait);
}
if(cleft>cright){
ll last=pA;
auto it = vals.lower_bound(pA); it++;
ll neww = *it;
resauxA+=(neww-last)*2*cright;
resauxA-=(neww-last)*2*cleft;
pA=neww;
}else{
break;
}
}
}
ll pB = -1;
ll resauxB = 0;
iset<pair<ll,ll>> leftB;
iset<pair<ll,ll>> rightB;
void acomodarB(){
while(true){
ll cleft=0;
auto lait = leftB.lower_bound({pB+1,-1});
if(lait!=leftB.end()){
cleft=SZ(leftB)-leftB.order_of_key(*lait);
}
ll cright=SZ(rightB);
auto rait = rightB.upper_bound({pB,1000000000000000});
if(rait!=rightB.end()){
cright=rightB.order_of_key(*rait);
}
if(cleft>cright){
ll last=pB;
auto it = vals.lower_bound(pB); it++;
ll neww = *it;
resauxB+=(neww-last)*2*cright;
resauxB-=(neww-last)*2*cleft;
pB=neww;
}else{
break;
}
}
}
bool cmp(const pair<ll,ll> &a, const pair<ll,ll> &b){
if(float(a.fst+a.snd)/float(2)<float(b.fst+b.snd)/float(2)) return true;
return false;
}
int main(){
ll k,n; cin>>k>>n;
ll resbase = 0;
forn(i,0,n){
char a,b;
ll l,r;
cin>>a>>l>>b>>r;
if(l>r) swap(l,r);
if(a!=b) rng.pb({l,r}),resbase++;
resbase+=r-l;
}
sort(ALL(rng),cmp); vals.insert(-1);
forn(i,0,SZ(rng)) vals.insert(rng[i].fst),vals.insert(rng[i].snd);
ll aux = 0;
forn(i,0,SZ(rng)) leftA.insert({rng[i].fst,aux}), aux++;
forn(i,0,SZ(rng)) rightA.insert({rng[i].snd,aux}), aux++;
forn(i,0,SZ(rng)){
resauxA+=(rng[i].fst+1)*2;
}
acomodarA();
//cout<<resauxA<<" "<<resauxB<<'\n';
ll mini = resbase+resauxA+resauxB;
if(k==1){
cout<<mini<<'\n';
return 0;
}
forn(i,0,SZ(rng)){
leftA.erase(leftA.lower_bound({rng[i].fst,0}));
rightA.erase(rightA.lower_bound({rng[i].snd,0}));
if(pA<rng[i].fst || pA>rng[i].snd) resauxA-=min(abs(pA-rng[i].fst),abs(pA-rng[i].snd))*2;
if(pB<rng[i].fst || pB>rng[i].snd) resauxB+=min(abs(pB-rng[i].fst),abs(pB-rng[i].snd))*2;
leftB.insert({rng[i].fst,aux}); aux++;
rightB.insert({rng[i].snd,aux}); aux++;
//cout<<resauxA<<'\n';
//cout<<"pres "<<pA<<" "<<pB<<'\n';
acomodarA();
acomodarB();
/*cout<<"pos "<<pA<<" "<<pB<<'\n';
cout<<i<<" "<<rng[i].fst<<" "<<rng[i].snd<<'\n';
cout<<resbase<<" "<<resauxA<<" "<<resauxB<<'\n';*/
mini=min(mini,resbase+resauxA+resauxB);
}
cout<<mini<<'\n';
return 0;
}
