#include <iostream>
#include <vector>
#include <random>
#include <algorithm>
using namespace std;
using ll = long long;
const ll INF = 1.77013e15;
const int MAXN = 100003;
pair<ll, ll> sg[MAXN];
ll pref_ans[MAXN];
ll suf_ans[MAXN];
signed main() {
int k, n = 0;
int n0;
cin >> k >> n0;
ll addans = 0;
for (int i = 0; i < n0; ++i) {
char c1, c2;
int d1, d2;
cin >> c1 >> d1 >> c2 >> d2;
if (d1 > d2)
swap(d1, d2);
d1 *= 2;
d2 *= 2;
if (c1 == c2) {
addans += d2 - d1;
} else {
sg[n] = {(d1 + d2) / 2, (d2 - d1) / 2};
++n;
}
}
sort(sg, sg + n);
if (k == 1) {
vector<int> event;
for (int i = 0; i < n; ++i) {
pair<ll, ll> t = sg[i];
event.push_back(t.first - t.second);
event.push_back(t.first + t.second);
}
sort(event.begin(), event.end());
ll x = event[n];
//cout << x << endl;
ll ans = 0;
for (int i = 0; i < n; ++i) {
ans += abs(x - sg[i].first + sg[i].second);
ans += abs(x - sg[i].first - sg[i].second);
}
cout << (ans + addans) / 2 + n << endl;
} else {
return 0;
}
}
