#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define PB push_back
#define FS first
#define SD second
#define EB emplace_back
#define ary(k) array<int,k>
template<class A,class B> void cmx(A& x, B y) {x=max<A>(x,y);}
template<class A,class B> void cmn(A& x, B y) {x=min<A>(x,y);}
typedef pair<int, int> pii;
typedef vector<int> vi;
signed main() {
cin.tie(0)->sync_with_stdio(0); cin.exceptions(cin.failbit);
int ans=0, k,n,a,b;
char c1,c2;
int mn=1e9, mx = 0;
cin >> k >> n;
vector<pii> v;
for(int i = 0;i<n;i++) {
cin >> c1 >> a >> c2 >> b;
if(c1 != c2) {
if(c1 == 'B') swap(a,b); // always A: pos, B: pos
v.EB(a,b);
cmn(mn,min(a,b));
cmx(mx,max(a,b));
ans++;
} else ans += abs(a-b);
}
// bsearch from mn to max
int l = mn, r = mx;
while(l<r){
int m1 = (l+r)/2;
int m2 = m1 + 1;
int cur1 = 0, cur2 = 0;
for(auto [a,b] : v) {
cur1 += abs(a-m1) + abs(b-m1);
cur2 += abs(a-m2) + abs(b-m2);
}
if(cur1 < cur2) {
r = m1;
} else l = m1+1;
}
assert(l==r);
// cerr << "chose " << l << "\n";
for(auto [a,b]:v) ans += abs(a-l) + abs(b-l);
cout << ans;
}
