#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
/*typedef __uint128_t L;
struct FastMod {
ull b, m;
FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
ull reduce(ull a) {
ull q = (ull)((L(m) * a) >> 64);
ull r = a - q * b; // can be proven that 0 <= r < 2*b
return r >= b ? r - b : r;
}
};
FastMod FM(2);*/
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << H;
debug_out(T...);
}
#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 1e5 + 10;
const ll inf = 1e18;
int n, k, x[maxn], y[maxn];
vector<int> num;
ll res, ans;
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> k >> n;
for (int i = 1; i <= n; i++){
char s, t; cin >> s >> x[i] >> t >> y[i];
if (x[i] > y[i]) swap(x[i], y[i]);
if (s == t){
res += y[i] - x[i];
x[i] = y[i] = -1;
continue;
}
num.push_back(x[i]);
num.push_back(y[i]);
}
if (num.empty()) return cout << res << '\n', 0;
sort(all(num));
num.resize(distance(num.begin(), unique(all(num))));
int N = num.size();
ll ans = inf;
for (int i = 0; i < N; i++){
for (int j = i+1; j < N; j++){
ll sum = 0;
for (int k = 1; k <= n; k++){
if (x[k] == -1) continue;
sum += min(abs(x[k] - num[i]) + abs(y[k] - num[i]), abs(x[k] - num[j]) + abs(y[k] - num[j])) + 1;
}
ans = min(ans, sum);
}
}
cout << ans + res << '\n';
return 0;
}
