#include <bits/stdc++.h>
#define int long long
using namespace std;
signed main() {
//freopen("1.in","r",stdin);
int k,n;
cin >> k >> n;
int ans=0;
vector<int> coord;
coord.reserve(2*n);
for (int i=0;i<n;i++) {
char c1,c2;
int x,y;
cin >> c1 >> x >> c2 >> y;
if (c1==c2) ans+=abs(x-y);
else {
coord.push_back(x);
coord.push_back(y);
}
}
sort(coord.begin(),coord.end());
vector<int> ps(coord.size()+1,0);
for (int i=0;i<coord.size();i++) {
ps[i+1]=ps[i]+coord[i];
}
int sz=coord.size();;
int mid=coord[sz/2-1];
// for (auto num:coord) cout<<num<<" ";
// cout<<"\n";
// for (int i=0;i<coord.size();i++) {
// cout<<ps[i]<<" ";
// }
// cout<<"\n";
int first_sum=ps[sz/2];
int second_sum=ps[coord.size()]-ps[sz/2];
ans+=second_sum-first_sum;
ans+=sz/2;
cout<<ans<<"\n";
return 0;
}
