#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
typedef long long ll;
typedef pair<long long, long long> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<long long> vl;
int k, n;
ll ans = 0;
vl ord;
int main(){
ios_base::sync_with_stdio(false);
cin>>k>>n;
for(int i = 0; i < n; i++){
char side1, side2;
ll p1, p2;
cin>>side1>>p1>>side2>>p2;
if(side1 == side2){
ans += abs(p1 - p2);
}
else
{
ord.pb(p1);
ord.pb(p2);
}
}
sort(ord.begin(), ord.end());
int sz = (int)ord.size();
ll pref[sz];
pref[0] = ord[0];
for(int i = 1; i < sz; i++)
pref[i] = pref[i-1] + ord[i];
ll best = 1e18;
for(int i = 0; i < sz; i++){
ll here = ans;
if(i+1 < sz)
{
here += pref[sz-1];
here -= pref[i];
here -= (sz - 1 - i) * ord[i];
}
if(i){
here -= pref[i-1];
here += i * ord[i];
}
here += (int)ord.size()/2;
best = min(best, here);
}
cout<<best<<endl;
return 0;
}
