#include <fstream>
using namespace std;

ifstream fin("datapal.in");
ofstream fout("datapal.out");
int n,i,j,ok,st,dr,maxs,nr,sec;
char d[9],f[100];
int main()
{
    fin>>n;
    for(i=1; i<=n; i++)
    {
        for(j=0; j<8; j++)fin>>d[j];
        ok=1;
        st=0;
        dr=7;
        while(st<dr&&ok==1)
            if(d[st]!=d[dr])ok=0;
            else
            {
                st++;
                dr--;
            }
        if(ok==1)
        {
            nr++;
            sec=(d[4]-'0')*10+d[5]-'0';
            f[sec]++;
            if(f[sec]>maxs)maxs=f[sec];
        }
    }
        fout<<nr<<'\n';

        for(i=0; i<=99; i++)if(f[i]==maxs) fout<<i+1<<' ';
        return 0;
    }