/// In The Name Of God
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define pp pop_back
#define mp make_pair
#define sz(x) (int)x.size()
#define sqr(x) ((x) * 1ll * (x))
#define all(x) x.begin(), x.end()
#define Kazakhstan ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define nl '\n'
#define ioi exit(0);
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int N = (int)1e5 + 7;
const int inf = (int)1e9 + 7;
const int mod = (int)1e9 + 7;
const ll linf = (ll)1e18 + 7;
const int dx[] = {-1, 0, 1, 0, 1, -1, -1, 1};
const int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
using namespace std;
int k, n;
ll add, ans = linf;
int p1[N], p2[N];
char t1[N], t2[N];
void calc(int p) {
ll cur = 0;
for (int i = 1; i <= n; i++) {
if (t1[i] == t2[i]) cur += abs(p1[i] - p2[i]);
else cur += abs(p - p1[i]) + abs(p - p2[i]);
}
ans = min(ans, cur);
}
int main() {
#ifdef IOI2018
freopen ("in.txt", "r", stdin);
#endif
Kazakhstan
cin >> k >> n;
for (int i = 1; i <= n; i++) {
cin >> t1[i] >> p1[i] >> t2[i] >> p2[i];
if (t1[i] != t2[i]) add++;
}
for (int i = 1; i <= n; i++) {
if (t1[i] == t2[i]) continue;
calc(p1[i]);
calc(p2[i]);
}
cout << ans + add;
ioi
}
