#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
struct A {
int x,y;
} s[100001];
bool cmp(A a, A b) {
return a.x+a.y<b.x+b.y;
}
int n,k;
ll ans,rsum,lsum,con,g[100001];
priority_queue<int> lsq;
priority_queue<int, vector<int>, greater<int>> rsq;
void add(int x) {
int median = lsq.empty() ? 1000000002 : lsq.top();
if (x<=median) lsq.push(x), lsum+=x;
else rsq.push(x), rsum+=x;
if (lsq.size() < rsq.size()) {
int k=rsq.top();
rsq.pop();
lsq.push(k);
rsum-=k;
lsum+=k;
}
if (lsq.size() > rsq.size()+1) {
int k=lsq.top();
lsq.pop();
rsq.push(k);
rsum+=k;
lsum-=k;
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>k>>n;
int idx=0;
for (int i=0; i<n; ++i) {
char a,b;
int x,y;
cin>>a>>x>>b>>y;
if (a==b) con+=abs(x-y);
else s[idx++]={x,y}, ++con;
}
sort(s,s+idx,cmp);
for (int i=0; i<idx; ++i) add(s[i].x), add(s[i].y), g[i]=rsum-lsum;
ans=rsum-lsum+con;
if (k==1) {
cout<<ans;
return 0;
}
while (!lsq.empty()) lsq.pop();
while (!rsq.empty()) rsq.pop();
lsum=0; rsum=0;
for (int i=idx-1; i>0; --i) {
add(s[i].x); add(s[i].y);
ans=min(ans,rsum-lsum+g[i-1]+con);
}
cout<<ans;
}
