#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i = a; i<int(b);++i)
#define all(v) v.begin(),v.end()
#define sz(v) v.size()
#define trav(a,c) for(auto a: c)
typedef long long ll;
typedef vector<ll> vi;
typedef pair<ll,ll> pii;
ll n,k;
vi points;
vector<pii> intervals;
ll getCost(vi bridges){
ll cost = 0;
rep(i,0,intervals.size()) {
ll dist = 1e18;
rep(j,0,k) {
if(bridges[j]<0||bridges[j]>=points.size()) return 1e18;
dist = min(dist,abs(points[bridges[j]]-intervals[i].first)+abs(points[bridges[j]]-intervals[i].second));
}
cost += dist;
}
return cost;
}
int main(){
cin.sync_with_stdio(false);
cin>>k>>n;
ll ans = 0;
rep(i,0,n){
char a,b;
ll c,d;
cin>>a>>c>>b>>d;
if(a==b){
ans += abs(c-d);
} else {
points.push_back(c);
points.push_back(d);
intervals.push_back({c,d});
ans++;
}
}
if(points.size()==0) {
cout<<ans<<endl;
return 0;
}
sort(all(points));
ll a = 0;
ll b = points.size()-1;
double jump = points.size()*10;
while(ll(jump)!=0){
//cout<<a<<" "<<b<<endl;
vi dirA = {1,0,-1,-1,-1,0,1,1,0};
vi dirB = {-1,-1,-1,0,1,1,1,0,0};
//if(k==1) rep(i,0,8) dirB[i] = 0;
ll bestDir = -1;
ll best = 1e18;
rep(i,0,9){
ll curr = getCost({a+dirA[i]*ll(jump),b+dirB[i]*ll(jump)});
if(curr<best){
bestDir = i;
best = curr;
}
}
a += dirA[bestDir]*ll(jump);
b += dirB[bestDir]*ll(jump);
jump*=0.9;
}
cout<<ans+getCost({a,b})<<endl;
}
