#include<bits/stdc++.h>
#define ll long long
using namespace std;
bool cmp(array<int,2> x,array<int,2> y)
{
return x[0] + x[1] < y[0] + y[1];
}
const int maxN = (int)1e5 + 2;
ll sum_left[maxN],sum_right[maxN];
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int k , n;
cin >> k >> n;
ll ans = 0;
if(k == 1)
{
vector<int> x_coords;
x_coords.clear();
while(n--)
{
char c1,c2;
int x1,x2;
cin >> c1 >> x1 >> c2 >> x2;
if(c1 == c2) ans += abs(x2 - x1);
else ++ans,x_coords.push_back(x1),x_coords.push_back(x2);
}
sort(x_coords.begin(),x_coords.end());
int med_idx = x_coords.size() / 2;
for(int x : x_coords) ans += abs(x - x_coords[med_idx]);
}
else
{
vector<array<int,2>> coords;
coords.clear();
while(n--)
{
int x1,x2;
char c1,c2;
cin >> c1 >> x1 >> c2 >> x2;
if(c1 == c2) ans += abs(x2 - x1);
else ++ans,coords.push_back({x1,x2});
}
sort(coords.begin(),coords.end(),cmp);
n = coords.size();
multiset<int> ms1,ms2;
ms1.clear(),ms2.clear();
ll l_sum = 0,r_sum = 0;
for(int i=0;i<n;++i)
{
int x1 = coords[i][0],x2 = coords[i][1];
if(x1 > x2) swap(x1,x2);
ms1.insert(x1),ms2.insert(x2);
l_sum += x1,r_sum += x2;
if(*ms2.begin() < *ms1.rbegin())
{
int v;
v = *ms2.begin();
ms2.erase(ms2.begin());
r_sum -= v;
ms1.insert(v);
l_sum += v;
v = *ms1.rbegin();
ms1.erase(ms1.find(v));
l_sum -= v;
ms2.insert(v);
r_sum += v;
}
ll median = *ms1.rbegin();
sum_left[i] = median * ms1.size() - l_sum + r_sum - median * ms2.size();
}
ms1.clear(),ms2.clear();
l_sum = 0,r_sum = 0;
for(int i=n-1;i>=0;--i)
{
int x1 = coords[i][0];
int x2 = coords[i][1];
if(x1 > x2) swap(x1,x2);
ms1.insert(x1),ms2.insert(x2);
l_sum += x1,r_sum += x2;
if(*ms1.rbegin() > *ms2.begin())
{
int v;
v = *ms2.begin();
ms2.erase(ms2.begin());
r_sum -= v;
ms1.insert(v);
l_sum += v;
v = *ms1.rbegin();
ms1.erase(ms1.find(v));
l_sum -= v;
ms2.insert(v);
r_sum += v;
}
ll median = *ms1.rbegin();
sum_right[i] = median * ms1.size() - l_sum + r_sum - median * ms2.size();
}
ll min_cost = LONG_LONG_MAX;
for(int i=0;i<n-1;++i) min_cost = min(min_cost,sum_left[i] + sum_right[i+1]);
ans += min({min_cost,sum_left[n-1],sum_right[0]});
}
cout << ans;
return 0;
}
