#include<bits/stdc++.h>
using namespace std;
const int N = 100'000 + 10;
int k, n;
pair<int, int> a[N];
long long sum = 0;
priority_queue<int> lt;
priority_queue<int, vector<int>, greater<>> rt;
void rearrange() {
if (lt.top() <= rt.top()) return;
int x = lt.top(), y = rt.top();
lt.pop(), rt.pop();
sum += 2 * x - 2 * y;
lt.push(y); rt.push(x);
}
void clr() {
sum = 0;
priority_queue<int> x;
priority_queue<int, vector<int>, greater<>> y;
swap(lt, x); swap(rt, y);
}
long long l[N], r[N];
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> k >> n;
long long add = 0;
for (int i = 1; i <= n; ++i) {
char A, B;
cin >> A >> a[i].first >> B >> a[i].second;
if (A != B) continue;
add += abs(a[i].first - a[i].second);
i -= 1; n -= 1;
}
sort(a + 1, a + n + 1, [&](const auto& a, const auto& b) {
return a.first + a.second < b.first + b.second;
});
for (int i = 1; i <= n; ++i) {
int x, y; tie(x, y) = a[i];
lt.push(x); rt.push(y);
sum += y - x;
rearrange();
l[i] = sum;
}
if (k == 1) {
cout << l[n] + add + n;
return 0;
}
clr();
for (int i = n; i >= 1; --i) {
int x, y; tie(x, y) = a[i];
lt.push(x); rt.push(y);
sum += y - x;
rearrange();
r[i] = sum;
}
long long answer = l[n];
for (int i = 2; i <= n; ++i) answer = min(answer, r[i] + l[i - 1]);
cout << answer + add + n << "\n";
}
