#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];
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];
}
int res = INF;
for(int i = 1;i <= n;i++)
{
int point = s[i];
int cur_res = 0;
for(int j = 1;j <= n;j++)
{
if(p[j] == q[j]){
cur_res += (abs(s[j] - t[j]));
continue;
}
cur_res += (abs(s[j] - point) + (abs(t[j] - point))) + 1;
}
res = min(res , cur_res);
point = t[i]; cur_res = 0;
for(int j = 1;j <= n;j++)
{
if(p[j] == q[j]){
cur_res += (abs(s[j] - q[j]));
continue;
}
cur_res += (abs(s[j] - point) + (abs(t[j] - point))) + 1;
}
res = min(res , cur_res);
}
cout << res << endl;
}
