#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef pair<int, int> ii;
typedef long long ll;
typedef pair<int, ll> pil;
const int len = 1e5+5, mx = 2e5, mx_ts = 1e9;
vector<ii> vec;
vector<int> cord, hel;
ll pref[len], suf[len];
map<int, int> mym;
/*
struct node{
int num;
ll sum;
node *lef, *rig;
node(int n = 0, ll s = 0, node *l = NULL, node *r = NULL){
num = n;
sum = s;
lef = l;
rig = r;
}
};
typedef node* pnode;
pnode null = new node(), root_lef, root_rig;
pnode add(pnode t, int l, int r, int i, int v){
pnode cur = t;
if (cur == null)
cur = new node(0, 0, null, null);
cur->num++;
cur->sum += v;
if (l == r)
return cur;
int mid = (l+r)/2;
if (i <= mid)
cur->lef = add(t->lef, l, mid, i, v);
else
cur->rig = add(t->rig, mid+1, r, i, v);
return cur;
}
pil ask(pnode t, int l, int r, int i, int j){
if (r < i || j < l)
return mp(0, 0);
if (i <= l && r <= j)
return mp(t->num, t->sum);
int mid = (l+r)/2;
pil lef = ask(t->lef, l, mid, i, j);
pil rig = ask(t->rig, mid+1, r, i, j);
return mp(lef.fi+rig.fi, lef.se+rig.se);
}
*/
struct bit{
pil tree[mx+4];
int rev;
bit(int r = 0){
rev = r;
}
void init(){
for (int i = 1; i <= mx; i++)
tree[i] = mp(0, 0);
}
void add(int i, int v){
if (rev)
i = mx-i+1;
while (i <= mx)
tree[i].fi++, tree[i].se += v, i += i&(-i);
}
pil ask(int i){
if (rev)
i = mx-i+1;
pil ans = mp(0, 0);
while (i > 0)
ans.fi += tree[i].fi, ans.se += tree[i].se, i -= i&(-i);
return ans;
}
};
bit lef = bit(1), rig = bit(0);
ll func(int pos){
pil le = lef.ask(mym[pos]);
pil ri = rig.ask(mym[pos]);
//printf("func(%d) = %lld\n", pos, (lef.se - pos*1LL*lef.fi) + (pos*1LL*rig.fi - rig.se));
return (le.se - pos*1LL*le.fi) + (pos*1LL*ri.fi - ri.se);
}
ll ts(){
int l = -1, r = (int)hel.size()-1;
while (l+1 < r){
int mid = (l+r)/2;
if (func(hel[mid]) < func(hel[mid+1]))
r = mid;
else
l = mid;
}
return func(hel[l+1]);
}
bool comp(ii a, ii b){
return (a.fi+a.se < b.fi+b.se);
}
int main(){
int k, n;
ll sum = 0;
scanf("%d %d", &k, &n);
for (int i = 0; i < n; i++){
char tpa, tpb;
int a, b;
scanf(" %c %d %c %d", &tpa, &a, &tpb, &b);
if (a > b)
swap(a, b);
sum += b-a;
if (tpa != tpb)
vec.pb(mp(a, b)), sum++;
}
int m = vec.size();
sort(vec.begin(), vec.end(), comp);
for (int i = 0; i < m; i++){
int a = vec[i].fi, b = vec[i].se;
cord.pb(a), cord.pb(b);
}
sort(cord.begin(), cord.end());
int cnt = 0;
for (int i = 0; i < cord.size(); i++)
if (i == 0 || cord[i] != cord[i-1])
hel.pb(cord[i]), mym[cord[i]] = ++cnt;
//printf("after sort:\n");
//for (int i = 0; i < m; i++)
// printf("(%d, %d)\n", vec[i].fi, vec[i].se);
//null->lef = null->rig = null;
//root_lef = root_rig = null;
lef.init(), rig.init();
for (int i = 0; i < m; i++){
//printf("building pref: i = %d\n", i);
int a = vec[i].fi, b = vec[i].se;
lef.add(mym[a], a);
rig.add(mym[b], b);
//root_lef = add(root_lef, 0, mx, mym[a], a);
//root_rig = add(root_rig, 0, mx, mym[b], b);
pref[i] = ts();
}
if (k == 1){
printf("%lld\n", sum+2*pref[m-1]);
return 0;
}
//root_lef = root_rig = null;
lef.init(), rig.init();
for (int i = m-1; i >= 0; i--){
int a = vec[i].fi, b = vec[i].se;
lef.add(mym[a], a);
rig.add(mym[b], b);
//root_lef = add(root_lef, 0, mx, mym[a], a);
//root_rig = add(root_rig, 0, mx, mym[b], b);
suf[i] = ts();
}
ll ans = pref[m-1];
for (int i = 0; i+1 < m; i++)
ans = min(ans, pref[i]+suf[i+1]);
//printf("ans = %lld, sum = %lld\n", ans, sum);
printf("%lld\n", 2*ans+sum);
return 0;
}
/*
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
