itmo_gonky

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}

bool sh = 0;

struct tim {
    int h, mn, s;
    void see() {
        cout << h << ' ' << mn << ' ' << s << "\n";
    }
};

int len(tim x) {
    return 3600 * x.h + 60 * x.mn + x.s;
}

bool cmp(tim a, tim b) {
    return len(a) < len(b);
}

int f(tim a, tim b) {
    int la = len(a), lb = len(b);
    if (sh) {
        cout << "a b\n";
        a.see();
        b.see();
        cout << "la lb = " << la << ' '<< lb << "\n";
    }
    if (lb - la < 0) {
        lb += 24 * 3600;
    }
    return lb - la;
}



tim con(string T) {

   /* if (sh) {
        cout << "time cnt\n";
        cout << T << "\n";
        cout << T[0] << ' ' << T[1] << "\n";
        cout << T[0] + T[1] << "\n";
    }*/
    int h = 10*(T[0]-'0') + T[1]-'0';
    int mn = 10*(T[3] - '0') + T[4] -'0';
    int s = 10*(T[6] - '0') + (T[7] - '0');
    return {h, mn, s};
}


int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, m;
    map <string, pair <tim, tim> > res;

    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int p;
        cin >> p;
        string nam; cin >> nam;
        if (res.find(nam) == res.end()) {
            res[nam].first = {-1, -1, -1};
            res[nam].second = {-1, -1, -1};
        }
        string Ti; cin >> Ti;
        if (p != 1 && p != n) {
            if (sh) {
                cout << "skip\n";
            }
            continue;
        }
        tim t = con(Ti);
        if (p == 1) {
            res[nam].first = t;
        } else {
            res[nam].second = t;
        }
        /*if (sh) {
            cout << "Ti = " << Ti << "\n";
            cout << "nam = " << nam << "\n";
            cout << "p = " << p << "\n";
            cout << "tim = "; t.see();
            cout << "\n";
        }*/
    }

    if (sh) {
        cout << "res\n";
        for (auto ex: res) {
            cout << ex.first << "\n";
            ex.second.first.see();
            ex.second.second.see();
            cout << "\n";
        }
    }


    vector < pair <int, string> > srt;
    for (auto ex: res) {
            int l = f(ex.second.first,  ex.second.second);
            if (ex.second.first.h == -1 || ex.second.second.h == -1) {
                continue;
            }
            srt.push_back({l, ex.first} );
            //ex.second.first.see();
            //ex.second.second.see();
        }
    if (sh) {
        cout << "srt\n";
        for (auto p: srt) {
            cout << p.first << ' ' << p.second << "\n";
        }
    }
    sort(srt.begin(), srt.end());
    vector <string> ans;
    int id = 0;
    while (srt.size() > 0 && id <= srt.size() - 1 && srt[id].first == srt[0].first) {
        ans.push_back(srt[id].second);
        id++;
    }
    cout << ans.size() << "\n";
    cvs(ans);
}