#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define endl "\n"
using namespace std;
using namespace __gnu_pbds;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T, typename key = less<T>>
using ordered_set = tree<T, null_type, key, rb_tree_tag, tree_order_statistics_node_update>;
void solve()
{
ll n, k;
cin >> k >> n;
vector<pair<ll, ll>> a;
vector<ll> l, r, v;
ll res = 0;
for (ll i = 0; i < n; i++)
{
ll x, y;
char c, d;
cin >> c >> x >> d >> y;
if (x > y) swap(x, y);
if (c != d)
a.push_back(make_pair(x, y)), v.push_back(x), v.push_back(y);
res += y - x;
}
n = a.size();
for (auto i : a)
l.push_back(i.first), r.push_back(i.second);
v.push_back(0);
ll ans = 2e18;
for (ll x : v)
{
ll sum = 0;
for (ll i : l)
if (i > x)
sum += i - x;
for (ll i : r)
if (i < x)
sum += x - i;
ans = min(ans, res + sum * 2 + n);
}
cout << ans << endl;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t = 1;
// precomp();
// cin >> t;
for (ll cs = 1; cs <= t; cs++)
solve();
// cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}
