#include<bits/stdc++.h>
#define pb push_back
#define x first
#define y second
using namespace std;
typedef long long ll;
const int N = 200345, MXN = N * 4;
int n, k, CS[N], CE[N], F[MXN];
pair < int , int > A[N];
vector < int > U, S[N], E[N];
inline void Add(int i, int val)
{
for (i ++; i < MXN; i += i & - i)
F[i] += val;
}
inline ll Get(int i)
{
int ret = 0;
for (i ++; i; i -= i & -i)
ret += F[i];
return (ret);
}
inline ll Solve1()
{
if (!n) return 0LL;
ll cntr = n, cntl = 0, tot = 0;
for (int i = 1; i <= n; i++)
{
CS[A[i].x] ++;
CE[A[i].y] ++;
tot += U[A[i].x] - U[0];
}
ll Mn = LLONG_MAX;
for (int i = 1; i < (int)U.size(); i++)
{
cntl += CE[i - 1];
tot += cntl * (U[i] - U[i - 1]);
tot -= cntr * (U[i] - U[i - 1]);
cntr -= CS[i];
Mn = min(Mn, tot);
}
return (Mn);
}
inline ll Solve2()
{
ll cntr = n, cntl = 0, tot = 0;
for (int i = 1; i <= n; i++)
{
S[A[i].x].pb(i);
E[A[i].y].pb(i);
tot += U[A[i].x] - U[0];
}
int r = 0;
ll Mn = LLONG_MAX, dft = 0;
for (int i = 1; i < (int)U.size(); i++)
{
tot -= cntr * (U[i] - U[i - 1]);
cntr -= (int)S[i].size();
for (int id : E[i - 1])
if (A[id].x > r)
Add(A[id].x - r - 1 + dft, 1);
dft ++;
while (r + 1 < i && cntl + (int)E[r].size() <= Get(dft))
{
cntl += (int)E[r].size();
tot += cntl * (U[r + 1] - U[r]);
tot -= Get(dft) * (U[r + 1] - U[r]);
for (int id : S[r + 1])
if (A[id].y < i)
Add(1 - (i - A[id].y) + dft, -1);
r ++; dft ++;
}
Mn = min(Mn, tot);
}
return (Mn);
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> k >> n;
ll tot = 0;
for (int i = 1; i <= n; i++)
{
char a, b;
cin >> a >> A[i].x >> b >> A[i].y;
if (A[i].y < A[i].x) swap(A[i].x, A[i].y);
tot += A[i].y - A[i].x;
if (a == b) {n --; i --; continue;}
A[i].x ++; U.pb(A[i].x);
A[i].y ++; U.pb(A[i].y);
tot ++;
}
U.pb(0);
sort(U.begin(), U.end());
U.resize(unique(U.begin(), U.end()) - U.begin());
for (int i = 1; i <= n; i++)
{
A[i].x = lower_bound(U.begin(), U.end(), A[i].x) - U.begin();
A[i].y = lower_bound(U.begin(), U.end(), A[i].y) - U.begin();
}
ll Mn1 = Solve1();
ll Mn2 = Solve2();
ll Mn = Mn1;
if (k == 2 && Mn2 < Mn)
Mn = Mn2;
return cout << tot + Mn + Mn << '\n', 0;
}
