#include <algorithm>
#include <numeric>
#include <iostream>
#include <cstring>
#include <numeric>
#include <vector>
#include <bitset>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int maxn = 2012;
bool isimp[maxn];
int hpos[maxn];
int wpos[maxn];
int imps[maxn];
map<int, int> pidx;
vector<int> poses = {0};
int stat[maxn];
int enat[maxn];
int ncnt[maxn];
int bcnt[maxn];
int menat[maxn];
ll nsum[maxn];
ll bsum[maxn];
ll dp[maxn][maxn];
int icnt = 0;
struct cmp
{
int l;
cmp(int _l)
{
l = _l;
}
inline int diff(int i)
{
//return hpos[i] - poses[l] + wpos[i] - poses.back();
return poses.back() + poses[l] - hpos[i] - wpos[i];
}
inline bool operator()(int i, int j)
{
return diff(i) > diff(j);
}
};
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n, k; cin >> k >> n; // k = 1
for(int i = 0; i < n; i++)
{
char a, b;
int c, d;
cin >> a >> c >> b >> d;
hpos[i] = min(c, d);
wpos[i] = max(c, d);
poses.push_back(c);
poses.push_back(d);
isimp[i] = (a != b);
}
sort(poses.begin(), poses.end());
poses.resize(unique(poses.begin(), poses.end()) - poses.begin());
poses.push_back(poses.back()+1);
const int m = poses.size();
for(int i = 0; i < m; i++)
{
pidx[poses[i]] = i;
}
for(int i = 0; i < n; i++)
{
if(isimp[i])
{
imps[icnt++] = i;
stat[pidx[hpos[i]]]++;
enat[pidx[wpos[i]]]++;
nsum[0] += hpos[i];
}
}
ncnt[0] = icnt;
for(int i = 1; i < m; i++)
{
ll x = poses[i] - poses[i-1];
ncnt[i] = ncnt[i-1] - stat[i-1];
bcnt[i] = bcnt[i-1] + enat[i-1];
nsum[i] = nsum[i-1] - x*ncnt[i];
bsum[i] = bsum[i-1] + x*bcnt[i];
}
for(int l = 0; l < m; l++)
{
vector<int> midimps;
memset(menat, 0, sizeof menat);
int bc = 0;
for(int idx = 0; idx < icnt; idx++)
{
int i = imps[idx];
if(hpos[i] > poses[l])
{
dp[l][m-1] += min(hpos[i] - poses[l], poses.back() - wpos[i]);
if(hpos[i] - poses[l] < poses.back() - wpos[i])
{
midimps.push_back(i);
}
else
{
menat[pidx[wpos[i]]]++;
bc++;
}
}
}
sort(midimps.begin(), midimps.end(), cmp(l));
//ll w = 0;
for(int r = m-2; r >= 0; r--)
{
dp[l][r] = dp[l][r+1];
ll w = poses[r+1] - poses[r];
dp[l][r] -= w * bc;
while(!midimps.empty() and hpos[midimps.back()] - poses[l] > poses[r] - wpos[midimps.back()])
{
dp[l][r] -= hpos[midimps.back()] - poses[l];
dp[l][r] += poses[r] - wpos[midimps.back()];
if(wpos[midimps.back()] < poses[r])
{
bc++;
menat[pidx[wpos[midimps.back()]]]++;
}
midimps.pop_back();
}
bc -= menat[r];
}
}
ll mndp = 1e17;
int anl = 0;
int anr = 0;
for(int l = 0; l < m; l++)
{
for(int r = 0; r < m; r++)
{
if(bsum[l] + dp[l][r] + nsum[r] < mndp)
{
mndp = bsum[l] + dp[l][r] + nsum[r];
anl = l;
anr = r;
}
}
}
cerr << anl << " " << anr << " " << mndp << endl;
ll out = 0;
for(int i = 0; i < n; i++)
{
if(isimp[i])
{
out += min( abs(wpos[i] - poses[anl]) + abs(hpos[i] - poses[anl]), abs(wpos[i] - poses[anr]) + abs(hpos[i] - poses[anr]) );
out++;
}
else
{
out += wpos[i] - hpos[i];
}
}
cout << out << endl;
return 0;
}
