#include <bits/stdc++.h>
using namespace std;
#define dbgv(v) cout<<#v<<" = "; f(i,0,v.size()) cout<<v[i]<<" "; cout<<endl
#define dbga(a,x,y) cout<<#a<<" = "; f(i,x,y) cout<<a[i]<<" "; cout<<endl
#define erorp(x) cout<<#x<<"={"<<(x.F)<<" , "<<x.S<<"}"<<endl
#define eror(x) cout<<#x<<'='<<(x)<<endl
#define f_(i,a,b) for(int i=a;i>=b;i--)
#define f(i,a,b) for(int i=a;i<b;i++)
#define nb(x) __builtin_popcount(x)
#define all(v) v.begin(),v.end()
#define bit(n,k) (((n)>>(k))&1)
#define Add(x,y) x=(x+y)%mod
#define maxm(a,b) a=max(a,b)
#define minm(a,b) a=min(a,b)
#define lst(x) x[x.size()-1]
#define sz(x) int(x.size())
#define mp make_pair
#define ll long long
#define pb push_back
#define S second
#define F first
#define int ll
const int N=2e5+99,inf=1e9;
int k,n,sum,ans,Sum[2][N],Cnt[2][N];
vector<pair<int,int>> a,b;
void addsum(int x,int val,int s){
for(x++;x<N;x+=x&-x) Sum[s][x]+=val;
}
void addcnt(int x,int val,int s){
for(x++;x<N;x+=x&-x) Cnt[s][x]+=val;
}
int getsum(int x,int s){
int res=0;
for(x++;x;x-=x&-x) res+=Sum[s][x];
return res;
}
int getcnt(int x,int s){
int res=0;
for(x++;x;x-=x&-x) res+=Cnt[s][x];
return res;
}
bool cmp(pair<int,int> i,pair<int,int> j){
return i.F+i.S<j.F+j.S;
}
vector<int> solve(vector<pair<int,int>> a){
f(s,0,2) f(i,0,N) Sum[s][i]=Cnt[s][i]=0;
vector<int> res,vec;
f(i,0,a.size()) vec.pb(a[i].F),vec.pb(a[i].S);
sort(all(vec));
vec.resize(unique(vec.begin(),vec.end())-vec.begin());
f(i,0,a.size()){
//erorp(a[i]);
int posl=lower_bound(all(vec),a[i].F)-vec.begin(),posr=lower_bound(all(vec),a[i].S)-vec.begin();
addcnt(posl,1,1);
addcnt(posr,1,0);
addsum(posl,a[i].F,1);
addsum(posr,a[i].S,0);
int l=-1,r=vec.size()-1;
while(l+1<r){
int mid=(l+r)>>1;
if(getcnt(mid,0)<=getcnt(vec.size()-1,1)-getcnt(mid,1)){
l=mid;
}
else{
r=mid;
}
}
l=r;
int pos=vec[l];
//eror(pos);
//eror(pos*getcnt(l,0)-getsum(l,0)+(getsum(vec.size()-1,1)));
res.pb(pos*getcnt(l,0)-getsum(l,0)+(getsum(vec.size()-1,1)-getsum(l,1))-pos*(getcnt(vec.size()-1,1)-getcnt(l,1)));
//cout<<cntb<<" "<<sumb<<" -- "<<cntf<<" "<<sumf<<endl;
//eror(res.back());
}
//cout<<"END"<<endl<<endl;
return res;
}
main(){
ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
cin>>k>>n;
f(i,0,n){
char c1,c2;
int l,r;
cin>>c1>>l>>c2>>r;
if(l>r) swap(l,r);
sum+=r-l;
if(c1==c2) continue ;
sum++;
a.pb({l,r});
b.pb({inf-r,inf-l});
}
if(a.size()==0) cout<<sum,exit(0);
sort(all(a),cmp);
sort(all(b),cmp);
vector<int> A=solve(a),B=solve(b);
//vector<int> B=solve(b);
ans=A.back();
f(i,0,A.size()-1){
minm(ans,A[i]+B[B.size()-i-2]);
}
if(k==1){
cout<<A.back()+A.back()+sum;
}
else{
cout<<ans+ans+sum;
}
}
/*
1 1
A 0 B 10
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
