#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)1e18;
vector<int> v;
vector<pii> seg;
set<pii> bef,dur,aft;
int t, n, sum_bef, sum_dur, sum_aft, tot, ans=LINF;
int tryy(set<pii> &S, int bri, int t){
if(S.empty()) return 0;
set<pii> bef,dur,aft; bef.clear(), dur.clear(), aft.clear();
vector<int> v; v.clear();
int sum_bef=0, sum_dur=0, sum_aft=0;
for(auto u : S){
v.pb(seg[u.se].fi), v.pb(seg[u.se].se);
aft.insert({min(seg[u.se].fi,seg[u.se].se),u.se});
sum_aft+=seg[u.se].fi+seg[u.se].se+1;
}
sort(all(v));
v.erase(unique(all(v)), v.end());
int ans = LINF;
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)+1;
if(t==1) sum_aft-=seg[i].fi+seg[i].se+1;
//else sum_aft-= either go to bri, or go to u;
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});
if(t==1) sum_bef+=min(2*u-seg[i].fi-seg[i].se+1, seg[i].fi+seg[i].se+1-2*bri);
else sum_bef+=seg[i].se+seg[i].fi+1;
sum_dur-=abs(seg[i].se-seg[i].fi)-1;
dur.erase(dur.begin());
}
if(t==0) ans = min(ans, sz(bef)*2*u-sum_bef+sum_dur+sum_aft);
else ans = min(ans, -sz(aft)*2*u+sum_dur+sum_aft+sum_bef);
}
return ans;
}
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);
}
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+1;
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)+1;
sum_aft-=seg[i].fi+seg[i].se+1;
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+1;
sum_dur-=abs(seg[i].se-seg[i].fi)-1;
dur.erase(dur.begin());
}
if(t==1) ans = min(ans, (sz(bef)-sz(aft))*2*u-sum_bef+sum_dur+sum_aft);
else{
ans = min(ans, tryy(bef,u,0)+sum_dur+sum_aft-sz(aft)*2*u);
ans = min(ans, sz(bef)*2*u-sum_bef+sum_dur+tryy(aft,u,1));
}
}
if(seg.empty()) ans=0;
cout << ans+tot;
}
