#include <bits/stdc++.h>
using namespace std;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int bridge_num, people_num;
cin >> bridge_num >> people_num;
long long ans = 0;
vector<pair<long long, long long>> intervals;
for (int i = 0; i < people_num; i++){
char P, Q;
long long S, T;
cin >> P >> S >> Q >> T;
if (P == Q) ans += abs(S - T);
else intervals.push_back({S, T});
}
sort(intervals.begin(), intervals.end(),
[](const pair<long long, long long> &a, const pair<long long, long long> &b)
{return a.first + a.second < b.first + b.second;});
people_num = intervals.size();
ans += people_num;
long long low_sum = 0, high_sum = 0;
priority_queue<long long> low;
priority_queue<long long, vector<long long>, greater<long long>> high;
auto insert = [&](long long val){
long long median = (low.empty() ? (long long)1e9 + 1 : low.top());
if (val <= median){
low_sum += val;
low.push(val);
}
else {
high_sum += val;
high.push(val);
}
if ((int)low.size() < (int)high.size()){
long long moving = high.top();
low_sum += moving;
high_sum -= moving;
low.push(moving);
high.pop();
}
else if ((int)low.size() > (int)high.size() + 1){
long long moving = low.top();
low_sum -= moving;
high_sum += moving;
high.push(moving);
low.pop();
}
};
vector<long long> pref(people_num + 1);
pref[0] = 0;
for (int i = 0; i < people_num; i++){
insert(intervals[i].first);
insert(intervals[i].second);
pref[i + 1] = high_sum - low_sum;
}
long long oppo_ans = pref[people_num];
if (bridge_num == 2){
while (!low.empty()) low.pop();
while (!high.empty()) high.pop();
low_sum = high_sum = 0;
for (int i = people_num - 1; i >= 0; i--){
insert(intervals[i].first);
insert(intervals[i].second);
oppo_ans = min(oppo_ans, high_sum - low_sum + pref[i]);
}
}
cout << ans + oppo_ans;
return 0;
}
