//#pragma warning( disable : 4996 )
#include <bits/stdc++.h>
//#pragma GCC target ("avx2")
//#pragma GCC optimization ("O3")
//#pragma GCC optimization ("unroll-loops")
using namespace std;
int N, K, temp1, temp2;
char tmp1, tmp2;
const int INTMAX = 2147483647;
int main()
{
/*
string problemName = "";
ifstream fin(problemName + ".in");
ofstream fout(problemName + ".out");
*/
ios::sync_with_stdio(0);
cin.tie(0);
cin >> K >> N;
if (K == 1) {
vector<pair<int,int>> significant;
map<int,int> starts;
map<int, int> ends;
long long int sum = 0;
int intervalnum = 0;
int starting;
int ending;
long long int curmin = INTMAX;
long long int cursum = 0;
for (int i = 0; i < N; i++) {
cin >> tmp1 >> temp1 >> tmp2 >> temp2;
if (tmp1 == tmp2) {
sum += abs(temp1 - temp2);
}
else if (temp1 == temp2) {
sum += 1;
}
else {
intervalnum++;
if (temp1 > temp2) {
swap(temp1, temp2);
}
sum += (1 + temp2 - temp1);
starts[temp1]++;
ends[temp2] ++;
significant.push_back({ temp1, 0 });
significant.push_back({ temp2, 1 });
}
}
sort(significant.begin(), significant.end());
/*
for (auto i : starts) {
cursum += 2 * (i.first - significant[0].first) * i.second;
}
*/
ending = 0;
starting = intervalnum - 1;
for (int i = 1; i < 2 * intervalnum; i++) {
curmin = min(cursum, curmin);
cursum += 2 * (significant[i].first - significant[i - 1].first) * (ending - starting);
if (significant[i].second) {
ending ++;
}
else {
starting --;
}
}
curmin = min(curmin, cursum);
cout << curmin + sum;
}
else {
}
}
