#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
const int N = 3e5 + 5;
const int oo = 1e18 + 7, mod = 1e9 + 7;
int n, k, a[N];
vector<pair<int, ii>> queries;
vector<int> diff;
int pref[N], suff[N];
ii IT1[N << 2], IT2[N << 2];
void upd1(int id, int val){
for(; id <= diff.size(); id += id & -id){
IT1[id].fi++;
IT1[id].se -= val;
}
}
ii get1(int id){
ii ans = {0, 0};
for(; id; id -= id & -id){
ans.fi += IT1[id].fi;
ans.se += IT1[id].se;
}
return ans;
}
void upd2(int id, int val){
for(; id <= diff.size(); id += id & -id){
IT2[id].fi--;
IT2[id].se += val;
}
}
ii get2(int id){
ii ans = {0, 0};
for(; id; id -= id & -id){
ans.fi += IT2[id].fi;
ans.se += IT2[id].se;
}
return ans;
}
/*
void upd1(int id, int l, int r, int pos, int val){
if(l == r){
IT1[id].fi++;
IT1[id].se -= val;
return;
}
int mid = (l + r) >> 1;
if(pos <= mid) upd1(id << 1, l, mid, pos, val);
else upd1(id << 1 | 1, mid + 1, r, pos, val);
IT1[id].fi = IT1[id << 1].fi + IT1[id << 1 | 1].fi;
IT1[id].se = IT1[id << 1].se + IT1[id << 1 | 1].se;
}*/
int cal(int x){
int pos = lower_bound(diff.begin(), diff.end(), x) - diff.begin();
ii temp1 = get1(pos);
ii temp2 = get2(diff.size() - 1), temp3 = get2(pos);
temp2.fi -= temp3.fi, temp2.se -= temp3.se;
temp1.fi += temp2.fi, temp1.se += temp2.se;
//get1(1, 1, diff.size() - 1, 1, pos);
//get2(1, 1, diff.size() - 1, pos, diff.size() - 1);
// cout << "OK " << x << " " << total.fi << " " << total.se << "\n";
return x * temp1.fi + temp1.se;
}
/*
2 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
void process(){
cin >> k >> n;
int answer = 0;
for(int i = 1; i <= n; i++){
char a, b;
int c, d;
cin >> a >> c >> b >> d;
if(a == b){
answer += abs(c - d);
continue;
}
queries.pb({c + d, {min(c, d), max(c, d)}});
diff.pb(c), diff.pb(d);
}
diff.pb(-1);
sort(queries.begin(), queries.end());
sort(diff.begin(), diff.end());
diff.resize(unique(diff.begin(), diff.end()) - diff.begin());
int cnt = 0;
for(auto it : queries){
// cout << it.fi << " " << it.se.fi << " " << it.se.se << "\n";
cnt++;
pref[cnt] = oo;
int posi1 = lower_bound(diff.begin(), diff.end(), it.se.fi) - diff.begin();
int posi2 = lower_bound(diff.begin(), diff.end(), it.se.se) - diff.begin();
//upd1(1, 1, diff.size() - 1, posi2, it.se.se);
//upd2(1, 1, diff.size() - 1, posi1, it.se.fi);
upd1(posi2, it.se.se);
upd2(posi1, it.se.fi);
int le = 1, ri = diff.size() - 1;
while(le < ri - 3){
int mid1 = (le + ri) >> 1, mid2 = mid1 + 1;
int x = cal(diff[mid1]), y = cal(diff[mid2]);
pref[cnt] = min(pref[cnt], min(x, y));
if(x > y) le = mid1;
else ri = mid2;
}
// cout << le << " " << ri << "\n";
for(int i = le; i <= ri; i++) pref[cnt] = min(pref[cnt], cal(diff[i]));
//cout << cnt << " " << pref[cnt] << "\n";
//total = {0, 0};
}
for(int i = 1; i <= (diff.size() << 2); i++){
IT1[i] = {0, 0}, IT2[i] = {0, 0};
}
reverse(queries.begin(), queries.end());
cnt = queries.size();
for(auto it : queries){
cnt--;
suff[cnt] = oo;
int posi1 = lower_bound(diff.begin(), diff.end(), it.se.fi) - diff.begin();
int posi2 = lower_bound(diff.begin(), diff.end(), it.se.se) - diff.begin();
//upd1(1, 1, diff.size() - 1, posi2, it.se.se);
//upd2(1, 1, diff.size() - 1, posi1, it.se.fi);
upd1(posi2, it.se.se);
upd2(posi1, it.se.fi);
int le = 1, ri = diff.size() - 1;
while(le < ri - 3){
int mid1 = (le + le + ri) / 3, mid2 = (le + ri + ri) / 3;
int x = cal(diff[mid1]), y = cal(diff[mid2]);
suff[cnt] = min(suff[cnt], min(x, y));
if(x > y) le = mid1;
else ri = mid2;
}
for(int i = le; i <= ri; i++) suff[cnt] = min(suff[cnt], cal(diff[i]));
//cout << cnt << " " << suff[cnt] << "\n";
}
int ans = oo;
for(int i = 0; i <= queries.size(); i++){
if(i && i < queries.size() && k == 1) continue;
ans = min(ans, pref[i] + suff[i]);
// cout << i << " " << pref[i] << " " << suff[i] << "\n";
}
ans *= 2;
ans += answer;
ans += queries.size();
for(auto it : queries) ans += abs(it.se.fi - it.se.se);
cout << ans;
//cout << ans << " " << ans + answer << "\n";
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
process();
}
/*
1 5
B 0 A 4
B 1 B 3
A 5 B 7
B 2 A 6
B 1 A 7
*/
