#include <bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pb push_back
using pii = pair<int,int>;
#define all(a) a.begin(),a.end()
#define sz(a) (int)a.size()
const int maxn = (int)1e5+10;
const int LINF = (int)4e18;
vector<int> v;
vector<pii> seg;
set<pii> bef,dur,aft;
int t, n, sum_bef, sum_dur, sum_aft, tot, ans=LINF;
/*
int arr[2][], cur[2];
set<pii>::iterator it[2];
int tryy(set<pii> &S, int t){
set<pii> bef,dur,aft; bef.clear(), dur.clear(), aft.clear();
vector<int> v; v.clear();
for(auto u : S) v.pb(seg[u.se])
v.erase(unique(all(v)), v.end());
for(int i = 0; i < sz(seg); i++)
aft.insert({min(seg[i].fi, seg[i].se),i}), sum_aft+=seg[i].fi+seg[i].se;
for(auto u : v){
while(!aft.empty() and aft.begin()->fi<=u){
int i = aft.begin()->se;
dur.insert({max(seg[i].fi, seg[i].se), i});
sum_dur+=abs(seg[i].se-seg[i].fi);
sum_aft-=seg[i].fi+seg[i].se;
aft.erase(aft.begin());
}
while(!dur.empty() and dur.begin()->fi<u){
int i = dur.begin()->se;
bef.insert({max(seg[i].fi, seg[i].se), i});
sum_bef+=seg[i].se+seg[i].fi;
sum_dur-=abs(seg[i].se-seg[i].fi);
dur.erase(dur.begin());
}
ans = min(ans, (sz(bef)-sz(aft))*2*u-sum_bef+sum_dur+sum_aft);
if(t==2){
ans = min(ans, tryy(bef,0)+sum_dur+sum_aft-sz(aft)*2*u);
ans = min(ans, tryy(aft,1)+sum_dur+sz(aft)*2*u-sum_bef);
}
}
if(seg.empty()) ans=0;
cout << ans+tot;
return min(arr[t][cur[t]], cur[t]+1);
}*/
int32_t main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> t >> n;
for(int i = 0; i < n; i++){
char a, c; int b, d;
cin >> a >> b >> c >> d;
if(a==c) tot+=abs(b-d);
else seg.pb({b,d}), v.pb(b), v.pb(d), tot++;
}
sort(all(v)); sort(all(seg));
v.erase(unique(all(v)), v.end());
for(int i = 0; i < sz(seg); i++)
aft.insert({min(seg[i].fi, seg[i].se),i}), sum_aft+=seg[i].fi+seg[i].se;
for(auto u : v){
while(!aft.empty() and aft.begin()->fi<=u){
int i = aft.begin()->se;
dur.insert({max(seg[i].fi, seg[i].se), i});
sum_dur+=abs(seg[i].se-seg[i].fi);
sum_aft-=seg[i].fi+seg[i].se;
aft.erase(aft.begin());
}
while(!dur.empty() and dur.begin()->fi<u){
int i = dur.begin()->se;
bef.insert({max(seg[i].fi, seg[i].se), i});
sum_bef+=seg[i].se+seg[i].fi;
sum_dur-=abs(seg[i].se-seg[i].fi);
dur.erase(dur.begin());
}
ans = min(ans, (sz(bef)-sz(aft))*2*u-sum_bef+sum_dur+sum_aft);
/*if(t==2){
ans = min(ans, tryy(bef,0)+sum_dur+sum_aft-sz(aft)*2*u);
ans = min(ans, tryy(aft,1)+sum_dur+sz(aft)*2*u-sum_bef);
}*/
}
if(seg.empty()) ans=0;
cout << ans+tot;
}
