#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;
char p[100005],q[100005];
ll x[100005],y[100005];
ll n;
vector<ll>vale;
ll solve(ll a,ll b){
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;
}
ll evre(ll x){
ll l = 0,r = vale.size()-2;
ll C = 1e18;
while(l <= r){
ll mid = (l+r)/2;
ll A = solve(x,vale[mid]);
ll B = solve(x,vale[mid+1]);
C = min(C,A);
C = min(C,B);
if(A >= B){
l = mid + 1;
}
else{
r = mid - 1;
}
}
return C;
}
int main(void){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll k;
cin>>k>>n;
assert(k == 2);
set<ll>ex;
ll res = 0;
f(i,0,n){
cin>>p[i]>>x[i]>>q[i]>>y[i];
ex.insert(x[i]);
ex.insert(y[i]);
if(p[i] != q[i]){
res++;
}
else{
res += abs(x[i] - y[i]);
}
}
for(auto x:ex){
vale.pb(x);
}
vale.pb(1e9);
ll l = 0,r = vale.size()-2;
while(l <= r){
ll mid = (l+r)/2;
ll a1 = 1e18,a2 = 1e18;
f(j,max(0LL,mid-10),mid+1){
a1 = min(a1,evre(vale[j]));
}
f(j,mid+1,min((ll)vale.size(),mid+10)){
a2 = min(a2,evre(vale[j]));
}
if(a1 >= a2){
l = mid + 1;
}
else{
r = mid - 1;
}
}
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
*/
