#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int NMAX = 1e5;
const int INF = 2e9;
int k, n, cnt_left, cnt_right, ind;
ll answer_c, answer, sum_inside, sum_left, sum_right;
pair<int, int> v[NMAX + 1];
struct Event {
int x, type, pos;
}events[2 * NMAX + 1];
bool cmp(const Event& a, const Event& b) {
return a.x < b.x;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> k >> n;
for(int i = 1; i <= n; i++) {
char p, q;
int a, b;
cin >> p >> a >> q >> b;
if(a > b) {
swap(a, b);
}
v[i] = {a, b};
if(p == q) {
answer_c += b - a; /// Cost = distance
}
else {
answer_c++; /// The bridge cost
cnt_left++;
sum_left += a + b;
events[++ind] = {a, 0, i};
events[++ind] = {b + 1, 1, i};
}
}
sort(events + 1, events + ind + 1, cmp);
int i = 1;
answer = sum_left;
while(i <= ind) {
int j = i;
while(j <= ind && events[i].x == events[j].x) {
auto [x, type, pos] = events[j];
auto [a, b] = v[pos];
if(!type) {
/// left erasing
cnt_left--;
sum_left -= a + b;
/// inside adding
sum_inside += b - a;
}
else {
/// inside erasing
sum_inside -= b - a;
/// right adding
cnt_right++;
sum_right += a + b;
}
j++;
}
answer = min(answer, sum_left - 2LL * cnt_left * events[i].x + sum_inside + 2LL * cnt_right * events[i].x - sum_right);
i = j;
}
cout << answer + answer_c << '\n';
return 0;
}
