#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define FOR(a , b) for(int i = a;i <= b;i++)
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MXN = 100005;
const int INF = 1e18;
const int mod = 1e9 + 7;
int k , n , s[MXN] , t[MXN];
char p[MXN] , q[MXN];
int calc(int pa , int pb)
{
int res = 0;
for(int i = 1;i <= n;i++)
{
if(p[i] == q[i])
{
res += (abs(s[i] - t[i]));
continue;
}
++res;
res += min((abs(s[i] - pa)) + (abs(t[i] - pa)) , (abs(s[i] - pb)) + (abs(t[i] - pb)));
}
return res;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> k >> n;
vector < int > pos; map < int , int > used;
for(int i = 1;i <= n;i++)
{
cin >> p[i] >> s[i] >> q[i] >> t[i];
if(!used[s[i]]){
pos.push_back(s[i]);
used[s[i]] = 1;
}
if(!used[t[i]]){
pos.push_back(t[i]);
used[t[i]] = 1;
}
}
int res = INF;
for(int i = 0;i < pos.size();i++)
{
int x = pos[i];
bool fi = 0;
for(int j = i - 1;j >= 1;j--)
{
if(calc(x , pos[j - 1]) > calc(x , pos[j])){
res = min(res , calc(x , pos[j]));
fi = 1;
break;
}
}
if(!fi && x != pos[0]) res = min(res , calc(x , pos[0]));
fi = 0;
for(int j = i + 1;j < pos.size() - 1;j++)
{
if(calc(x , pos[j + 1]) > calc(x , pos[j])){
res = min(res , calc(x , pos[j]));
fi = 1;
break;
}
}
if(!fi && x != pos[pos.size() - 1]) res = min(res , calc(x , pos[pos.size() - 1]));
}
cout << res << endl;
}
