#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 200005;
template<class T, int SZ> struct BIT {
T bit[SZ+1];
BIT() { memset(bit,0,sizeof bit); }
void upd(int k, T val) { // add val to index k
for( ;k <= SZ; k += (k&-k)) bit[k] += val;
}
T query(int k) {
T temp = 0;
for (;k > 0;k -= (k&-k)) temp += bit[k];
return temp;
}
T query(int l, int r) { return query(r)-query(l-1); } // range query [l,r]
};
BIT<ll,MX> s[2];
int K,N;
ll ans = 0, mn = INF;
vpi v;
map<int,int> m;
vi rm;
pl cur;
pl operator+(const pl& l, const pl& r) { return {l.f+r.f,l.s+r.s}; }
pl operator-(const pl& l, const pl& r) { return {l.f-r.f,l.s-r.s}; }
ll eval(int x) {
return s[1].query(x)*rm[x]+s[0].query(x);
}
void ad(int ind, int l, int r, int x) {
s[ind].upd(l,x);
s[ind].upd(r+1,-x);
}
void ins(int a, int b) {
ad(1,1,m[a],-1);
ad(0,1,m[a],a);
ad(1,m[b],sz(m),1);
ad(0,m[b],sz(m),-b);
}
ll pre(int x) {
return cur.s*rm[x]-cur.f;
}
void compress() {
int co = 0;
rm.resize(sz(m)+1);
rm.pb(-1);
for (auto& a: m) {
a.s = ++co;
rm[co] = a.f;
}
}
void getmn() {
compress();
sort(all(v),[](pi a, pi b){ return a.f+a.s < b.f+b.s; });
int ind = sz(m);
vl ans1(sz(v));
F0Rd(i,sz(v)) {
ins(v[i].f,v[i].s);
while (ind > 1 && eval(ind-1) < eval(ind)) ind --;
ans1[i] = eval(ind);
}
vl ans2(sz(v));
s[0] = s[1] = BIT<ll,MX>();
ind = 1;
F0R(i,sz(v)) {
ins(v[i].f,v[i].s);
while (ind < sz(m) && eval(ind+1) < eval(ind)) ind ++;
ans2[i] = eval(ind);
}
mn = ans1[0];
if (K == 2) {
F0R(i,sz(v)-1) mn = min(mn,ans1[i+1]+ans2[i]);
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> K >> N;
m[0] = 0;
F0R(i,N) {
char a1, b1; int a2, b2;
cin >> a1 >> a2 >> b1 >> b2;
ans += abs(a2-b2);
if (a1 != b1) {
v.pb({min(a2,b2),max(a2,b2)});
ans ++;
m[a2] = m[b2] = 0;
}
}
if (sz(v) == 0) {
cout << ans;
exit(0);
}
getmn();
cout << ans+2*mn;
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
