#include <bits/stdc++.h>
#define int long long
#define sz(x) (long long)(x.size())
using namespace std;
struct traj{
int l, r;
long double mid;
};
vector <traj> a;
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int K, N; cin >> K >> N;
int ans(0);
for (int i(0); i < N; i++) {
char riv1, riv2;
int pos1, pos2;
cin >> riv1 >> pos1 >> riv2 >> pos2;
if (pos2 < pos1) swap(pos1, pos2);
if (riv1 != riv2) {
ans++;
a.push_back ({pos1, pos2, (long double)( (pos1 + pos2) / 2)});
}
else ans += pos2 - pos1;
}
if (sz(a) == 0){
cout << ans << '\n';
return 0;
}
sort (a.begin(), a.end(), [](traj &A, traj &B){return A.mid < B.mid;});
priority_queue <int> left;
priority_queue <int, vector<int>, greater <int>> right;
vector <int> score (sz(a)), score2 (sz(a));
int median = a[0].l;
left.push(a[0].l);
right.push(a[0].r);
score[0] = a[0].r - a[0].l;
for (int i(1); i < sz(a); i++) {
score[i] = score[i - 1] + abs(a[i].l - median) + abs(a[i].r - median);
if (a[i].l > left.top()) right.push(a[i].l);
else left.push(a[i].l);
if (a[i].r <= left.top()) left.push(a[i].r);
else right.push(a[i].r);
int szL = sz(left), szR = sz(right);
while (left.size() > right.size()) {
right.push(left.top());
left.pop();
}
while (left.size() < right.size()) {
left.push(right.top());
right.pop();
}
int newmedian = left.top();
if (newmedian > median) {
score[i] += szL * (newmedian - median);
score[i] -= szR * (newmedian - median);
}
else {
score[i] -= (szL -1) * (median - newmedian);
score[i] += (szR + 1) * (median - newmedian);
}
median = newmedian;
}
if (K == 1) {
cout << ans + score[sz(a) - 1] << '\n';
return 0;
}
while (!left.empty()) left.pop();
while(!right.empty()) right.pop();
median = a[sz(a) - 1].l;
left.push(a[sz(a) - 1].l);
right.push(a[sz(a) - 1].r);
score2[sz(a) - 1] = (a[sz(a) - 1].r - median);
int best = min(score[sz(a) - 1], score[sz(a) - 2] + score2[sz(a) - 1]);
for (int i(sz(a) - 2); i > 0; i--) {
score2[i] = score2[i + 1] + abs(a[i].l - median) + abs(a[i].r - median);
if (a[i].l > left.top()) right.push(a[i].l);
else left.push(a[i].l);
if (a[i].r <= left.top()) left.push(a[i].r);
else right.push(a[i].r);
int szL = sz(left), szR = sz(right);
while (left.size() > right.size()) {
right.push(left.top());
left.pop();
}
while (left.size() < right.size()) {
left.push(right.top());
right.pop();
}
int newmedian = left.top();
if (newmedian > median) {
score2[i] += szL * (newmedian - median);
score2[i] -= szR * (newmedian - median);
}
else {
score2[i] -= (szL - 1) * (median - newmedian);
score2[i] += (szR + 1) * (median - newmedian);
}
median = newmedian;
best = min(best, score[i - 1] + score2[i]);
}
cout << best + ans << '\n';
return 0;
}
