#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
typedef long long ll;
using namespace std;
struct segment { int l, r; };
vector<ll> solve(const vector<segment>& s) // l a r budu 1 indexovane
{
int n = s.size()-1, j = 0;
vector<int> v;
for (int i = 1; i <= n; i++) v.push_back(s[i].l), v.push_back(s[i].r);
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
vector<ll> ans(n + 1, 0);
ll cntr = 0, sumr = 0, cntl = 0, suml = 0;
auto eval = [&cntl, &cntr, &suml, &sumr](ll x)
{
return cntr * x - sumr + suml - cntl * x;
};
multiset<int> sl, sr;
for (int i = 1; i <= n; i++)
{
sl.insert(s[i].l), sr.insert(s[i].r);
cntl++, suml += s[i].l;
while (true)
{
while (!sl.empty() && *sl.begin() <= v[j])
{
cntl--, suml -= *sl.begin();
sl.erase(sl.begin());
}
while (!sr.empty() && *sr.begin() <= v[j])
{
cntr++, sumr += *sr.begin();
sr.erase(sr.begin());
}
if (j == v.size() - 1 || v[j + 1] * 2 >= s[i].l + s[i].r || eval(v[j]) < eval(v[j + 1])) break;
j++;
}
ans[i] = eval(v[j]);
}
return ans;
}
bool cmp(const segment& a, const segment& b) { return a.l + a.r < b.l + b.r; }
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int k, n;
cin >> k >> n;
vector<segment> v(1, { 0, 0 });
ll sum = 0;
for (int i = 0; i < n; i++)
{
char c1, c2; int l1, l2;
cin >> c1 >> l1 >> c2 >> l2;
if (c1 != c2) v.push_back({ min(l1, l2), max(l1, l2) }), sum++;
sum += abs(l1 - l2);
}
n = v.size()-1;
sort(v.begin()+1, v.end(), cmp);
vector<ll> ans1 = solve(v);
if (k == 1)
{
cout << ans1[n]*2 + sum << "\n";
return 0;
}
reverse(v.begin() + 1, v.end());
for (int i = 1; i <= n; i++) v[i] = { -v[i].r, -v[i].l };
vector<ll> ans2 = solve(v);
ll ans = 1e18;
for (int i = 0; i <= n; i++)
{
ans = min(ans, ans1[i] + ans2[n - i]);
}
cout << ans*2 + sum << "\n";
return 0;
}
