#include<bits/stdc++.h>
using namespace std;
struct node{
char p,q;
int s,t;
void inn(){
cin>>p>>s>>q>>t;
}
};
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int k,n;cin>>k>>n;
map<int,int>mp;
vector<node>arr(n);
vector<int>brr;
for (int i = 0;i<n;++i){
arr[i].inn();
if (arr[i].p!=arr[i].q){
brr.push_back(arr[i].s);
brr.push_back(arr[i].t);
}
}
const long long mxn = 1e15;
sort(brr.begin(),brr.end());
if (k == 1 || n == 1){
long long ans = mxn;
for (int i = 0;i<2;++i){
long long curans = 0;
int temp = (int)brr.size()/2 - 1 + i;
for (int j = 0;j<n;++j){
if (arr[j].p == arr[j].q){
curans+=abs(arr[j].t - arr[j].s);
}
else{
curans+=abs(arr[j].t - brr[temp]) + abs(arr[j].s - brr[temp]) + 1;
}
}
ans = min(ans,curans);
}
cout<<ans<<'\n';
}
else{
vector<int>pos;
pos.push_back(brr.size() / 2 - 1);
pos.push_back(brr.size() / 2);
pos.push_back(brr.size() / 4);
pos.push_back(brr.size() / 4 + 1);
pos.push_back(brr.size() / 4 * 3);
pos.push_back(brr.size() / 4 * 3 + 1);
long long ans = mxn;
for (auto x:pos){
for (auto y:pos){
long long curans = 0;
for (int j = 0;j<n;++j){
if (arr[j].p == arr[j].q){
curans+=abs(arr[j].t - arr[j].s);
}
else{
curans+=min(abs(arr[j].t - brr[x]) + abs(arr[j].s - brr[x]),abs(arr[j].t - brr[y]) + abs(arr[j].s - brr[y])) + 1;
}
}
ans = min(curans,ans);
}
}
cout<<ans<<'\n';
}
return 0;
}
