#include<stdio.h>
#include<math.h>
#include<algorithm>
#define MAX_N 100005
#define abs(x) ((x)>0?(x):(-(x)))
#define LL long long
using namespace std;
struct emp{
int x,y;
};
emp arr[MAX_N];
LL N,K;
LL only_arr[2*MAX_N],ans;
LL input(){
LL i,n,S,T,sum=0;
char P[2],Q[2];
n=0;
for(i=0;i<N;i++){
scanf("%s %lld %s %lld",P,&S,Q,&T);
if(P[0]==Q[0]){
sum+=abs(S-T);
}else{
only_arr[2*n+1]=S;only_arr[2*n+2]=T;
arr[++n].x=S;arr[n].y=T;
sum++;
}
}
N=n;
return sum;
}
LL bridge_only(){
LL i,x,sum=0;
sort(only_arr+1,only_arr+2*N+1);
x=N;
for(i=1;i<=2*N;i++) sum+=abs(only_arr[i]-only_arr[x]);
return sum;
}
LL cost(LL x,LL y,LL P,LL Q){
LL i,p,q,sum=0;
for(i=1;i<=N;i++){
if(i==x || i==y) continue;
p=abs(P-arr[i].x)+abs(P-arr[i].y);
q=abs(Q-arr[i].x)+abs(Q-arr[i].y);
p=p<q?p:q;
sum+=p;
}
return sum;
}
LL proper(LL x,LL y){
LL p,q,r,s;
p=cost(x,y,arr[x].x,arr[y].x);
q=cost(x,y,arr[x].x,arr[y].y);
r=cost(x,y,arr[x].y,arr[y].x);
s=cost(x,y,arr[x].y,arr[y].y);
p=p<q?p:q;
r=r<s?r:s;
p=p<r?p:r;
return abs(arr[x].x-arr[x].y)+abs(arr[y].x-arr[y].y)+p;
}
int main(){
LL base;
scanf("%lld %lld",&K,&N);
base=input();
ans=bridge_only()+base;
if(K==1){
printf("%lld\n",ans);
return 0;
}
//O(N^3)
LL i,j,k,x;
for(i=1;i<=N;i++){
for(j=i+1;j<=N;j++){
x=proper(i,j)+base;
ans=ans<x?ans:x;
}
}
printf("%lld\n",ans);
return 0;
}
