/* Bismillahir Rahmanir Rahim */
#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
const long long oo = 1e18;
int k, n;
long long pos[N][2];
char fk[N][2];
void solve_big(){
long long ret = oo;
for(int i = 1; i <= n; i++){
for(int a = 0; a <= 1; a++){
for(int j = 1; j <= n; j++){
for(int b = 0; b <= 1; b++){
long long ans = 0;
for(int f = 1; f <= n; f++){
if(fk[f][0] == fk[f][1]){
ans += abs(pos[f][1] - pos[f][0]);
continue;
}
long long aa = 1LL + abs(pos[f][0] - pos[i][a]) + abs(pos[f][1] - pos[i][a]);
long long bb = 1LL + abs(pos[f][0] - pos[j][b]) + abs(pos[f][1] - pos[j][b]);
ans += min(aa, bb);
}
ret = min(ret, ans);
}
}
}
}
cout << ret << endl;
}
void solve_small(){
long long ret = oo;
for(int i = 1; i <= n; ++i){
for(int a = 0; a <= 1; a++){
long long ans = 0;
for(int f = 1; f <= n; f++){
if(fk[f][0] == fk[f][1]){
ans += abs(pos[f][1] - pos[f][0]);
continue;
}
long long aa = 1LL + abs(pos[f][0] - pos[i][a]) + abs(pos[f][1] - pos[i][a]);
ans += aa;
}
ret = min(ret, ans);
}
}
cout << ret << endl;
}
int main(){
cin >> k >> n;
for(int i = 1; i <= n; i++){
for(int j = 0; j <= 1; j++){
cin >> fk[i][j] >> pos[i][j];
}
}
if(k == 1) solve_small();
else solve_big();
return 0;
}
