#include <bits/stdc++.h>
using namespace std;
typedef pair<long long, long long> ii;
bool comp(ii a, ii b){
return a.first + a.second < b.first + b.second;
}
int main()
{
//freopen("i.txt","r",stdin);
int k, n;
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> k >> n;
vector<ii> pairs;
long long forcedDist = 0ll;
for(int i = 0;i < n;i++){
char a, c;
long long b, d;
cin >> a >> b >> c >> d;
if(a == c){
forcedDist += abs(d-b);
}
else{
forcedDist += abs(d-b);
forcedDist++;
if(b > d) swap(b,d);
pairs.push_back(ii(b,d));
}
}
n = pairs.size();
if(n == 0){
cout << forcedDist;
return 0;
}
sort(pairs.begin(),pairs.end(),comp);
for(int i = 0;i < n;i++){
//cout << pairs[i].first << " " << pairs[i].second << "\n";
}
long long prefix[n];
long long suffix[n];
priority_queue<long long> low;
priority_queue<long long, vector<long long>, greater<long long> > high;
long long minVal = 0;
for(int i = 0;i < n;i++){
long long p = pairs[i].first;
long long q = pairs[i].second;
if(low.empty()){
low.push(p);
high.push(q);
}
else{
if(low.top() >= q){
low.push(p);
low.push(q);
minVal += abs(low.top() - q);
high.push(low.top());
low.pop();
}
else if(high.top() <= p){
high.push(p);
high.push(q);
minVal += abs(high.top() - p);
low.push(high.top());
high.pop();
}
else{
low.push(p);
high.push(q);
}
}
prefix[i] = minVal;
}
if(k == 1){
cout << prefix[n-1] * 2ll + forcedDist;
return 0;
}
reverse(pairs.begin(),pairs.end());
while(!low.empty())low.pop();
while(!high.empty())high.pop();
minVal = 0;
for(int i = 0;i < n;i++){
long long p = pairs[i].first;
long long q = pairs[i].second;
if(low.empty()){
low.push(p);
high.push(q);
}
else{
if(low.top() >= q){
low.push(p);
low.push(q);
minVal += abs(low.top() - q);
high.push(low.top());
low.pop();
}
else if(high.top() <= p){
high.push(p);
high.push(q);
minVal += abs(high.top() - p);
low.push(high.top());
high.pop();
}
else{
low.push(p);
high.push(q);
}
}
suffix[i] = minVal;
}
reverse(suffix,suffix+n);
//cout << "\n";
long long mv = suffix[0];
for(int i = 1;i < n;i++){
//cout << suffix[i] << " ";
mv = min(prefix[i-1] + suffix[i], mv);
}
cout << mv * 2ll + forcedDist;
return 0;
}
