#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N,M,Q;
map<int, vector<int>> C;
int R[111];

int g(char c) {
    return c-'0';
}

void solve() {
    cin>>N>>M;
    
    int d;
    string t;
    REP(i,M) {
        cin>>d>>t;
        int s = d*10000 + g(t[0])*1000 + g(t[1])*100 + g(t[3])*10 + g(t[4]);
        cin>>d>>t;
        int e = d*10000 + g(t[0])*1000 + g(t[1])*100 + g(t[3])*10 + g(t[4]);
        C[e].push_back(s);
    }
    REP(i,N)R[i]=0;
    int ans = 0;
    for (auto p:C) {
        sort(ALL(p.second));
        for (auto c:p.second) {
            int mi = -1;
            REP(i,N) if (R[i]<c){
                if (mi<0 || R[mi]<R[i]) mi=i;
            }
            if (mi>-1) {
                ans++;
                R[mi] = p.first;
            }
        }
    }
    
    cout << ans << endl;
}