#include <bits/stdc++.h>
#define all(x) x.begin(),x.end()
#define pii pair<int, int>
#define ft first
#define sd second
#define MP make_pair
#define PB push_back
#define sz(x) ((int)x.size())
using namespace std;
typedef long long ll;
const ll PW = 43;
const int N = 10010;
const int B = 100;
const int oo = 2e9;
const ll OO = 1e18;
vector<pii> seg, sem;
vector<int> pts, segl, segr;
ll extra = 0, best = OO, kl = 0, kr = 0, sl = 0, sr = 0, lft[N], rgt[N], chkl[N], chsm[N], dob[N];
int k, n, siz;
bool cmp(pii _x, pii _y){
return _x.sd < _y.sd;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("in.txt","r",stdin);
cin >> k >> n;
for (int i = 0; i < n; i++){
char c1, c2; int l, r;
cin >> c1 >> l >> c2 >> r;
if (l > r) swap(l, r);
extra += r - l;
if (c1 != c2){
extra++;
segl.PB(l);
segr.PB(r);
seg.PB(MP(l, r));
pts.PB(l);
pts.PB(r);
}
}
sort(all(pts));
pts.resize(unique(all(pts)) - pts.begin());
sort(all(segl));
sort(all(segr));
siz = sz(segr);
if (k == 2){
for (int i = 0; i < siz; i++){
kl++;
sl += segl[i];
}
for (int i = 0; i < sz(pts); i++){
int x = pts[i];
while (kl > 0 && segl[siz - kl] <= x){
sl -= segl[siz - kl];
kl--;
}
lft[i] = sl - (ll(x) * kl);
while (kr < siz && segr[kr] < x){
sr += segr[kr];
kr++;
}
rgt[i] = (ll(x) * kr) - sr;
}
for (int i1 = 0; i1 < sz(pts); i1++){
int x = pts[i1];
sem.clear();
for (pii cr : seg)
if (cr.ft > x)
sem.PB(cr);
sort(all(sem), cmp);
int it = 0;
ll add = 0, kol = 0, sum;
for (int i2 = i1; i2 < sz(pts); i2++){
int y = pts[i2];
ll cur = lft[i2] + rgt[i1];
while (it < sz(sem) && sem[it].sd < y){
pii se = sem[it];
if (se.ft - x < y - se.sd){
add += se.ft - x;
} else {
kol++; sum += se.sd;
if (se.ft - x < pts.back() - se.sd){
int ll = i2, rr = sz(pts) - 1;
while (ll < rr){
int md = (ll + rr) >> 1;
if (se.ft - x < pts[md] - se.sd)
rr = md;
else ll = md + 1;
}
dob[ll] += se.ft - x;
chkl[ll]++;
chsm[ll] += se.sd;
}
}
it++;
}
add += dob[i2];
sum -= chsm[i2];
kol -= chkl[i2];
dob[i2] = chsm[i2] = chkl[i2] = 0;
cur += add + (kol * ll(y)) - sum;
best = min(best, cur + cur);
}
}
if (best == OO)
best = 0;
cout << best + extra;
return 0;
}
for (int i = 0; i < siz; i++){
kl++;
sl += segl[i];
}
for (int x : pts){
while (kl > 0 && segl[siz - kl] <= x){
sl -= segl[siz - kl];
kl--;
}
while (kr < siz && segr[kr] < x){
sr += segr[kr];
kr++;
}
ll cur = sl - (ll(x) * kl) + (ll(x) * kr) - sr;
best = min(best, cur + cur);
}
if (best == OO)
best = 0;
cout << best + extra;
return 0;
}
