#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ii,ll>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
ll anss = 1e18;
ll solve(ll a,ll b,ll x[],ll y[],ll n){
ll ans = 0;
f(i,0,n){
if(p[i] != q[i]){
ans += min(abs(a - x[i]) + abs(a - y[i]),abs(b - x[i]) + abs(b - y[i]));
}
}
anss = min(ans,anss);
return ans;
}
int main(void){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll szpos = 0,szneg = 0;
map<ll,ll>mp;
ll sumpos = 0,sumneg = 0;
ll k,n;
cin>>k>>n;
assert(k == 2);
char p[n],q[n];
ll s[n],t[n];
set<ll>ex;
ll res = 0;
f(i,0,n){
cin>>p[i]>>s[i]>>q[i]>>t[i];
ex.insert(s[i]);
ex.insert(t[i]);
if(p[i] != q[i]){
res++;
}
else{
res += abs(s[i] - t[i]);
}
}
vector<ll>vale;
for(auto x:ex){
vale.pb(x);
}
vale.pb(1e9);
for(auto x:vale){
for(auto y:vale){
solve(x,y,s,t,n);
}
}
cout<<anss + res<<"\n";
}
/*
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
