#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main()
{
    ll m, s;
    cin >> m >> s;
    vector<vector<ll>> z1(m);
    for (int i = 0; i < m; i++)
    {
        for (int j = 0; j < s; j++)
        {
            ll a;
            cin >> a;
            z1.at(i).push_back(a);
        }
    }
    map<ll, ll> z2;
    ll r;
    bool crt;
    ll we;
    for (int i = 0; i < s; i++)
    {
        we = i;
        for (int j = 0; j < m; j++)
        {
            z2[z1.at(j).at(i)] += 1;
        }
        crt = true;
        for (auto x : z2)
        {
            if (x.second != 3)
            {
                crt = false;
                break;
            }
        }
        if (crt == true)
        {
            r = i + 1;
            break;
        }
    }
    if (crt == false)
    {
        r = we + 1;
    }
    cout << r << endl;
    z1.at(0).resize(r);
    sort(z1.at(0).begin(), z1.at(0).end());
    for (int i = 0; i < r; i++)
    {
        cout << z1.at(0).at(i) << " ";
    }
    cout << endl;
    return 0;
}