#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for(ll i = a; i < ll(b); ++i)
#define trav(a, v) for(auto& a : v)
#define all(x) x.begin(), x.end()
#define sz(x) (ll)(x).size()
#define D(x) cerr << #x << " = " << x << endl
typedef long long ll;
typedef pair<ll, ll> pii;
typedef vector<ll> vi;
#include <ext/pb_ds/assoc_container.hpp> /** keep-include */
#include <ext/pb_ds/tree_policy.hpp> /** keep-include */
using namespace __gnu_pbds;
template <class T>
using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int main() {
cin.sync_with_stdio(false);
ll k,n;
ll totDist = 0;
vector<pair<ll,pii>> intervals;
cin>>k>>n;
rep(i,0,n){
char a,b;
ll c,d;
cin>>a>>c>>b>>d;
if(a!=b){
intervals.push_back(make_pair(c+d,pii(c,d)));
}else{
totDist += abs(c-d);
}
}
ll bestDist = 0;
if(intervals.size()>1){
sort(all(intervals));
vi rightTmp;
vi leftTmp;
rep(i,0,intervals.size()){
if(i == 0){
leftTmp.push_back(intervals[i].second.first);
leftTmp.push_back(intervals[i].second.second);
}else{
rightTmp.push_back(intervals[i].second.first);
rightTmp.push_back(intervals[i].second.second);
}
}
multiset<ll> right(rightTmp.begin(),rightTmp.end());
multiset<ll> left(leftTmp.begin(),leftTmp.end());
auto rAt = right.begin();
advance(rAt, right.size()/2);
ll rIndex = right.size()/2;
ll rSum = 0;
for(auto it : right) rSum += abs(it - *rAt);
auto lAt = left.begin();
ll lIndex = 0;
ll lSum = abs(intervals[0].second.second-intervals[0].second.first);
bestDist = lSum + rSum;
rep(i,1,intervals.size()-1){
ll a = intervals[i].second.first;
ll b = intervals[i].second.second;
lSum += abs(*lAt-a) + abs(*lAt-b);
rSum -= abs(*rAt-a) + abs(*rAt-b);
vector<ll> p(2);
p[0] = a; p[1] = b;
rep(i,0,2){
if(p[i]<*lAt) ++lIndex;
left.insert(p[i]);
if(p[i]==*rAt){
auto eraseAt = rAt;
if(rIndex>0){
--rIndex;
rAt = prev(rAt);
}else{
rAt = next(rAt);
}
right.erase(eraseAt);
}else{
if(p[i]<*rAt) --rIndex;
right.erase(right.find(p[i]));
}
}
if(lIndex>0){
--lIndex;
lAt = prev(lAt);
lSum -= (lIndex*2 + 2 - left.size())*(*(next(lAt)) - *lAt);
}
if(rIndex>0){
--rIndex;
rAt = prev(rAt);
rSum -= (rIndex*2 + 2 - right.size())*(*(next(rAt)) - *rAt);
}
//assert(distance(left.begin(),lAt)==lIndex);
while(lIndex<left.size()/2){
lSum += (lIndex*2 + 2 - left.size())*(*(next(lAt)) - *lAt);
advance(lAt,1);
++lIndex;
}
//assert(distance(right.begin(),rAt)==rIndex);
while(rIndex<right.size()/2){
rSum += (rIndex*2 + 2 - right.size())*(*(next(rAt)) - *rAt);
advance(rAt,1);
++rIndex;
}
bestDist = min(bestDist,lSum + rSum);
}
}else if(intervals.size()==1){
bestDist = abs(intervals[0].second.second - intervals[0].second.first);
}
totDist += bestDist;
totDist += intervals.size();
cout<<totDist<<endl;
}
/*left.insert(a);
if(a<*lAt){
++lIndex;
//lAt = next(lAt);
}
left.insert(b);
if(b<*lAt){
++lIndex;
//lAt = next(lAt);
}
rSum -= abs(*rAt-a) + abs(*rAt-b);
if(a == *rAt){
auto eraseAt = rAt;
if(rIndex!=right.size()-1)
rAt = next(rAt);
else{
rAt = prev(rAt);
--rIndex;
}
right.erase(eraseAt);
//rAt = prev(rAt);
}else{
if(a<*rAt){
--rIndex;
right.erase(right.lower_bound(a));
//rAt = prev(rAt);
}else{
right.erase(right.lower_bound(a));
}
}
if(b == *rAt){
auto eraseAt = rAt;
if(rIndex!=right.size()-1)
rAt = next(rAt);
else{
rAt = prev(rAt);
--rIndex;
}
right.erase(eraseAt);
//rAt = prev(rAt);
}else{
if(b<*rAt){
--rIndex;
//rAt = prev(rAt);
}
right.erase(right.lower_bound(b));
}
if(lIndex>0){
--lIndex;
lAt = prev(lAt);
--lIndex;
lAt = prev(lAt);
}
if(rIndex>0){
--rIndex;
lAt = prev(lAt);
--rIndex;
lAt = prev(lAt);
}*/
