#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define eb emplace_back
#define mt make_tuple
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
const ll INF=LLONG_MAX;
const int mxn=1e5+5;
bool DEBUG=0;
int n,k;
vll coor;
vector<pll>str;
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
cin >> k >> n;
ll ans = 0ll;
for(int i=0; i<n; i++){
char hs,of; ll hos,off;
cin >> hs >> hos >> of >> off;
if(hs==of){
ans += (abs(hos-off));
}else{
if(hos>off)swap(hos,off);
ans+=off-hos+1ll;
str.eb(hos,off);
coor.eb(hos);
coor.eb(off);
}
}
sort(all(coor));
//k=1
int bridge1=coor[sz(str)-1],bridge2=coor[sz(str)];
ll res1=0ll,res2=0ll;
for(int i=0; i<sz(str); i++){
if(bridge1<str[i].fi){
res1 += 2ll*(str[i].fi-bridge1);
}else if(bridge1>str[i].se){
res1 += 2ll*(bridge1-str[i].se);
}
if(bridge2<str[i].fi){
res2 += 2ll*(str[i].fi-bridge2);
}else if(bridge2>str[i].se){
res2 += 2ll*(bridge2-str[i].se);
}
}
ans += min(res1,res2);
cout << ans << '\n';
}
// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN
