#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
#define f first
#define s second
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 point)
{
int res = 0;
for(int i = 1;i <= n;i++)
{
if(p[i] == q[i])
{
res += (abs(s[i] - t[i]));
continue;
}
++res;
res += (abs(s[i] - point)) + (abs(t[i] - point));
}
return res;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin >> k >> n;
for(int i = 1;i <= n;i++)
{
cin >> p[i] >> s[i] >> q[i] >> t[i];
}
vector < int > pos;
for(int i = 1;i <= n;i++) pos.push_back(s[i]) , pos.push_back(t[i]);
sort(pos.begin() , pos.end());
int pointer = 0;
int res = INF;
while(pointer < pos.size()){
res = min(res , calc(pos[pointer]));
++pointer;
}
cout << res << endl;
}
