/* made by amunduzbaev */
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define ff first
#define vv vector
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define sz(x) (int)x.size()
#define tut(x) array<int, x>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define NeedForSpeed ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define int long long
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vii;
typedef vector<pii> vpii;
template<class T> bool umin(T& a, const T& b) { return a > b? a = b, true:false; }
template<class T> bool umax(T& a, const T& b) { return a < b? a = b, true:false; }
//void usaco(string s) { freopen((s+".in").c_str(),"r",stdin);
//freopen((s+".out").c_str(),"w",stdout); }
//template<class T> tree<T,
//less<T>, null_type, rb_tree_tag,
//tree_order_statistics_node_update> ordered_set;
const int N = 2e5+5;
const int mod = 1e9+7;
const ll inf = 1e18;
const ld Pi = acos(-1);
#define MULTI 0
int n, m, k, ans, q, res, a[N];
int pref[N], suf[N], tcnt[N], l[N], r[N];
int pre[N], in[N], pre2[N];
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
vpii tt;
vii tmp;
//void dnc(int l = 0, int r = n-1, int lx = 0, int rx = n-1){
//if(r > l) return;
//int i = (l + r)>>1;
//int opt = -1, mn = inf;
//for(int j=lx;j<=min(rx, j);j++){
//int m = lb(all(tt), (pii){(tt[i].ff + tt[j].ff + 1)>>1, 0}) - tt.begin();
//int m2 = --lb(all(tt), (pii){(tt[i].ff + tt[j].ff + 2)>>1, 0}) - tt.begin();
//assert(abs(m - m2) <= 1);
//if(umin(mn, pref[j] + suf[i] + (pref[i] - pref[m]) + (suf[j] - suf[m2]) + abs(tt[m].ff - tt[m2].ff) * tcnt[m])) opt = j;
//} assert(~opt);
//umin(ans, mn);
//dnc(l, i-1, lx, opt);
//dnc(i+1, r, opt, rx);
//}
void solve(int t_case){
cin>>k>>n;
for(int i=0, last = 0;i<n;i++){
char s1, s2; int p1, p2;
cin>>s1>>p1>>s2>>p2;
if(s1 == s2) res += abs(p1 - p2);
else l[last] = min(p1, p2), r[last] = max(p1, p2), last++, m = last;
} n = m;
for(int i=0;i<n;i++){
tt.pb({l[i], 0});
tt.pb({r[i], 1});
} sort(all(tt));
n = sz(tt);
int cost = 0, cnt = 0, cntl = 0, last = 0;
for(int i=0;i<n;){
int j = i;
if(last) pref[last] = abs(tt[i-1].ff - tt[i].ff) * cnt * 2 + abs(tt[i-1].ff - tt[i].ff) * cntl + pref[last-1];
while(j < n && tt[i].ff == tt[j].ff) j++;
tmp.pb(tt[i].ff);
while(i < j) {
if(tt[i].ss) cntl--, cnt++;
else cntl++;
i++;
} pre[last] = cnt, tcnt[last++] = cntl;
}
//for(auto x : tt) cout<<x.ff<<" ";
//cout<<"\n";
//for(auto x : tt) cout<<x.ss<<" ";
//cout<<"\n";
reverse(all(tt));
cnt = cntl = cost = 0;
int tll = 0;
for(int i=0;i<n;){
int j = i;
if(tll) suf[last - tll - 1] = abs(tt[i-1].ff - tt[i].ff) * cnt * 2 + abs(tt[i-1].ff - tt[i].ff) * cntl + suf[last - tll];
while(j < n && tt[i].ff == tt[j].ff) j++;
while(i < j) {
if(!tt[i].ss) cntl--, cnt++;
else cntl++;
i++;
} pre2[last - tll - 1] = cnt, tll++;
} ans = (n ? inf : 0);
n = last;
//cout<<"\n";
for(int i=0;i<n;i++) umin(ans, pref[i] + suf[i]);
//for(int i=0;i<n;i++) { if(i > 0 && i < 4) cout<<" ";
//cout<<pref[i]<<" "; }
//cout<<"\n";
//for(int i=0;i<n;i++) { if(i > 4) cout<<" ";
//cout<<suf[i]<<" "; }
//cout<<"\n";
//for(int i=0;i<n;i++) cout<<pre[i]<<" ";
//cout<<"\n";
//for(int i=0;i<n;i++) cout<<tcnt[i]<<" ";
//cout<<"\n";
//for(int i=0;i<n;i++) cout<<pre2[i]<<" ";
//cout<<"\n";
//cout<<"\n";
if(k > 1){
//dnc();
for(int i=0;i<n;i++){
for(int j=0;j<i;j++){
for(int m=j;m<=i;m++){
int cost = pref[j] + suf[i] + (pref[i] - pref[m] - pre[m] * abs(tmp[i] - tmp[m]) * 2) +
(suf[j] - suf[m] - pre2[m] * abs(tmp[m] - tmp[j]) * 2) + abs(tmp[m] - tmp[m]) * tcnt[m];
//cout<<i<<" "<<m<<" "<<j<<" "<<cost<<"\n";
umin(ans, cost);
}
}
}
}
//cout<<res<<" "<<ans<<" "<<m<<"\n";
cout<<res + ans + m<<"\n";
}
signed main(){
NeedForSpeed
if(!MULTI) {
solve(1);
} else {
int t; cin>>t;
for(int t_case = 1; t_case <= t; t_case++) solve(t_case);
} return 0;
}
