/*
* Task: apio15_bridges
* Lang: C/C++11
* Site: oj.uz
* Last Update: 19/3/2018
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
/* Note
----------------------------
Learned :
Bugs found & solved :
Optimizations :
----------------------------
*/
#define x first
#define y second
#define umap unordered_map
#define pqueue priority_queue
#define mset multiset
#define mp make_pair
#define mt make_tuple
#define all(x) x.begin(),x.end()
#define long long long
#define MOD 1000000007
#define MAX (int)(1e9+5)
#define MIN (int)(-1e9-5)
#define FILEIN_ freopen("__in.txt","r",stdin)
#define FILEOUT_ freopen("__out.txt","w",stdout)
#define FILEIO_ freopen("__in.txt","r",stdin),freopen("__out.txt","w",stdout)
#define FILEIN(text) freopen(text,"r",stdin)
#define FILEOUT(text) freopen(text,"w",stdout)
#define FILEIO(text) freopen(text".in","r",stdin),freopen(text".out","w",stdout)
template<typename T>using oset=tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
char c1[5],c2[5];
pair<long,long> a[100005];
vector<long> pos(1,0);
long sml[600005],smll[600005],smls[600005],smr[600005],smrl[600005],smrs[600005],best[100005];
umap<long,long> wh;
void sm_upl(long tidx,long l,long r,long x,long y,long w,long s){
long mid = (l+r)/2;
if(x > r || y < l){
return;
}
if(x <= l && y >= r){
smll[tidx] += w;
smls[tidx] += (pos[y]-pos[r])*2*w + s;
sml[tidx] += (pos[y]-pos[r])*2*w + s + ((pos[r]-pos[l])*(pos[r]-pos[l]+1))*w;
return;
}
if(smll[tidx] || smls[tidx]){
sm_upl(tidx*2,l,mid,l,r,smll[tidx],smls[tidx]);
sm_upl(tidx*2+1,mid+1,r,l,r,smll[tidx],smls[tidx]);
smll[tidx] = smls[tidx] = 0;
}
sm_upl(tidx*2,l,mid,x,y,w,s);
sm_upl(tidx*2+1,mid+1,r,x,y,w,s);
sml[tidx] = sml[tidx*2] + sml[tidx*2+1];
}
void sm_upr(long tidx,long l,long r,long x,long y,long w,long s){
long mid = (l+r)/2;
if(x > r || y < l){
return;
}
if(x <= l && y >= r){
smrl[tidx] += w;
smrs[tidx] += (pos[l]-pos[x])*2*w + s;
smr[tidx] += (pos[l]-pos[x])*2*w + s + ((pos[r]-pos[l])*(pos[r]-pos[l]+1))*w;
return;
}
if(smrl[tidx] || smrs[tidx]){
sm_upr(tidx*2,l,mid,l,r,smrl[tidx],smrs[tidx]);
sm_upr(tidx*2+1,mid+1,r,l,r,smrl[tidx],smrs[tidx]);
smrl[tidx] = smrs[tidx] = 0;
}
sm_upr(tidx*2,l,mid,x,y,w,s);
sm_upr(tidx*2+1,mid+1,r,x,y,w,s);
smr[tidx] = smr[tidx*2] + smr[tidx*2+1];
}
long sm_get(long tidx,long l,long r,long x){
long mid = (l+r)/2;
if(x > r || x < l){
return 0;
}
if(x <= l && x >= r){
return sml[tidx] + smr[tidx];
}
if(smll[tidx] || smls[tidx]){
sm_upl(tidx*2,l,mid,l,r,smll[tidx],smls[tidx]);
sm_upl(tidx*2+1,mid+1,r,l,r,smll[tidx],smls[tidx]);
smll[tidx] = smls[tidx] = 0;
}
if(smrl[tidx] || smrs[tidx]){
sm_upr(tidx*2,l,mid,l,r,smrl[tidx],smrs[tidx]);
sm_upr(tidx*2+1,mid+1,r,l,r,smrl[tidx],smrs[tidx]);
smrl[tidx] = smrs[tidx] = 0;
}
return sm_get(tidx*2,l,mid,x) + sm_get(tidx*2+1,mid+1,r,x);
}
bool rs(pair<int,int> x,pair<int,int> y){
return ((double)(x.x+x.y))/2 < ((double)(y.x+y.y))/2;
}
main(){
long t,i,j,k,n,m,x,y,res=0,mn=MAX,v;
oset<int> apos;
scanf("%lld %lld",&k,&n);
for(i = 1; i <= n; i++){
scanf("%s %lld %s %lld",c1,&x,c2,&y);
x++;
y++;
if(x > y) swap(x,y);
res += abs(y-x);
if(c1[0] == c2[0]){
n--;
i--;
continue;
}
a[i] = {x,y};
res++;
pos.emplace_back(x);
pos.emplace_back(y);
}
if(!n){
printf("%d\n",res);
return 0;
}
sort(all(pos));
pos.resize(unique(all(pos))-pos.begin());
m = pos.size()-1;
sort(a+1,a+1+n,rs); // sort be mean of x and y then do brute force division
for(i = 0; i < pos.size(); i++){
wh[pos[i]] = i;
}
for(i = 1; i <= n; i++){
x = a[i].x;
y = a[i].y;
apos.insert(x);
apos.insert(y);
sm_upl(1,1,m,1,wh[x],1,0);
sm_upr(1,1,m,wh[y],m,1,0);
best[i] = sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2)]); // greedy : best is the middle positions
if(apos.size()/2+1 < apos.size()) best[i] = min(best[i],sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2+1)]));
if(apos.size()/2-1 > 0) best[i] = min(best[i],sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2-1)]));
}
if(k == 1){
printf("%lld\n",res+best[n]);
return 0;
}
memset(sml,0,sizeof sml);
memset(smll,0,sizeof smll);
memset(smls,0,sizeof smls);
memset(smr,0,sizeof smr);
memset(smrl,0,sizeof smrl);
memset(smrs,0,sizeof smrs);
apos.clear();
mn = best[n];
for(i = n; i >= 1; i--){
x = a[i].x;
y = a[i].y;
apos.insert(x);
apos.insert(y);
sm_upl(1,1,m,1,wh[x],1,0);
sm_upr(1,1,m,wh[y],m,1,0);
mn = min(mn,sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2)]) + best[i-1]);
if(apos.size()/2+1 < apos.size()) mn = min(mn,sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2+1)]) + best[i-1]);
if(apos.size()/2-1 > 0) mn = min(mn,sm_get(1,1,m,wh[*apos.find_by_order(apos.size()/2-1)]) + best[i-1]);
}
printf("%lld\n",mn+res);
return 0;
}
