#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define endl '\n'
#define MASK(i) (1LL << (i))
#define ull unsigned long long
#define ld long double
#define pb push_back
#define all(x) (x).begin() , (x).end()
#define BIT(x , i) ((x >> (i)) & 1)
#define TASK "task"
#define sz(s) (int) (s).size()
using namespace std;
const int mxN = 3e5 + 227;
const int inf = 1e9 + 277;
const int mod = 1e9 + 7;
const ll infll = 1e18 + 7;
const int base = 307;
const int LOG = 20;
template <typename T1, typename T2> bool minimize(T1 &a, T2 b) {
if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b) {
if (a < b) {a = b; return true;} return false;
}
struct item{
int b1 , z1 , b2 , z2;
} a[mxN];
int n , k;
int val[mxN];
ll f(int x)
{
ll res = 0;
for(int i = 1 ; i <= n ; i++)
{
if(a[i].z1 == a[i].z2) res += abs(a[i].b1 - a[i].b2);
else {
res += abs(x - a[i].b1) + abs(x - a[i].b2) + 1;
}
}
return res;
}
void solve()
{
cin >> k >> n;
for(int i = 1 ; i <= n ; i++) {
char c1 , c2;
cin >> c1 >> a[i].b1 >> c2 >> a[i].b2;
a[i].z1 = (c1 == 'A' ? 1 : 2);
a[i].z2 = (c2 == 'A' ? 1 : 2);
}
int cnt = 0;
for(int i = 1 ; i <= n ; i++) {
if(a[i].z1 == a[i].z2) continue;
val[++cnt] = a[i].b1;
val[++cnt] = a[i].b2;
}
sort(val + 1 , val + 1 + cnt);
cout << f(val[(cnt + 1) / 2]);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
// freopen(TASK".inp" , "r" , stdin);
// freopen(TASK".out" , "w" , stdout);
int tc = 1;
//cin >> tc;
while(tc--) {
solve();
}
return 0;
}
