#include <bits/stdc++.h>
#define ll long long
#define f first
#define s second
using namespace std;
const int MAXN = 1e5+5;
bool cmp(pair<int,int> a, pair<int,int> b){
return a.f+a.s < b.f+b.s;
}
ll X[2][MAXN]; pair<int,int> dif[MAXN];
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int K,N; cin >> K >> N;
ll ans = 0;
vector<int> vec; int n = 1;
for(int i = 0;i<N;++i){
char p1,p2; int S,T; cin >> p1 >> S >> p2 >> T;
if(p1 != p2){
vec.push_back(S); vec.push_back(T);
dif[n].f = S; dif[n].s = T; ++n; ++ans;
}
else{
ans += abs(S-T);
}
}
--n;
if(K == 1){
if(!vec.size()){
cout << ans << "\n";
return 0;
}
sort(vec.begin(),vec.end());
int med = vec[vec.size()/2];
for(int i = 1;i<=n;++i){
ans += abs(dif[i].f-med)+abs(dif[i].s-med);
}
cout << ans << "\n";
}
else{
sort(dif+1,dif+n+1,cmp);
priority_queue<int,vector<int>,less<int>> pq1; priority_queue<int,vector<int>,greater<int>> pq2; //pq1: decreasing, pq2: increasing
ll lsum = 0, rsum = 0;
for(int i = 1;i<=n;++i){
pq1.push(dif[i].f); pq1.push(dif[i].s);
lsum += dif[i].f+dif[i].s; rsum += pq1.top(); lsum -= pq1.top();
pq2.push(pq1.top()); pq1.pop();
if(pq1.top() > pq2.top()){
int tmp1 = pq1.top(), tmp2 = pq2.top();
pq1.pop(); pq2.pop();
pq1.push(tmp2); pq2.push(tmp1);
lsum += tmp2-tmp1; rsum -= tmp2-tmp1;
}
X[0][i] = rsum-lsum; //distance of the median to everything
}
while(!pq1.empty()){
pq1.pop();
}
while(!pq2.empty()){
pq2.pop();
}
lsum = rsum = 0;
for(int i = n;i>=1;--i){
pq1.push(dif[i].f); pq1.push(dif[i].s);
lsum += dif[i].f+dif[i].s; rsum += pq1.top(); lsum -= pq1.top();
pq2.push(pq1.top()); pq1.pop();
if(pq1.top() > pq2.top()){
int tmp1 = pq1.top(), tmp2 = pq2.top();
pq1.pop(); pq2.pop();
pq1.push(tmp2); pq2.push(tmp1);
lsum += tmp2-tmp1; rsum -= tmp2-tmp1;
}
X[1][i] = rsum-lsum;
}
ll val = 1e18;
for(int i = 1;i<=n+1;++i){
val = min(val,X[0][i-1]+X[1][i]); //first bridge for the first i-1, second for the others
}
cout << val+ans << "\n";
}
/*2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7*/
return 0;
}
